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[Question] [ Closed. This question is [off-topic](/help/closed-questions). It is not currently accepting answers. --- You are asking questions about a story set in a world instead of about building a world. For more information, see [Why is my question "Too Story Based" and how do I get it opened?](https://worldbuilding.meta.stackexchange.com/q/3300/49). Closed 1 year ago. [Improve this question](/posts/238559/edit) I am currently building a world where most of the realm is primordial and extremely hostile to human life with humans worship of an angel(With each angel being specific to that settlement.) warding off the darkness and keeping things solid. If the faith of the community falters then the protection bestowed upon them also falters which can result in a breach. How would such a society deal with someone who is found out to be a non-believer whether it be through their diary being revealed or them loudly complaining? [Answer] The obvious answer is exile. You don't believe? OK, pack your things and fend for yourself outside in the darkness. The problem with your idea however is that any unbeliever who wishes to can simply mimic whatever cycle of prayer or ritual the community requires while personally having no commitment whatsoever to its ideals at all. And of course unless they are very careless no-one will ever know. Given the potentially severe punishment they face no unbeliever is going to talk about their agnosticism/atheism let alone leave written evidence of it for others to find. The only circumstances where such might be possible would be where there is an organized 'network' or secret society of unbelievers who are hiding within one or more of the communities. That however would require some kind of backstory on your part to explain why it exists in a world where apparently faith is essential for mankind to survive. Perhaps for example they secretly worship the darkness because they believe (rightly or wrongly) that generations ago a pact was made by their ancestors with the darkness on the promise that if they could undermine the faith of the communities to the point where the towns collapsed they and their descendants would be spared/rewarded. [Answer] Just look at theocratic regimes on earth over the centuries. Most will shun unbelievers at the very least, many will actively persecute them and either exile them, forcibly convert them, or kill them (often the same religion will do all three at different times and places). And the true believers are excellent religious police, just make it a holy duty to weed out the heretics and either kill them or turn them over to the inquisition. You might even create a system where a new convert has to prove his faith by killing say 10 heretics for you, or by serving in a function in the armed forces where there is a very high risk of death for those who aren't true believers (I assume your deity grants special protection to his faithful on patrols in the wilderness and will withhold that protection from the unbelievers). [Answer] # Frame challenge: there are no non-believers In such a setting you can probably very directly prove the existence of angels. And very directly prove the existence of needing their protection. Assuming a non-believer exists, they can be convinced of real actual presence of all the supernatural things. Such a society would most likely reinforce this by having demonstration of the reality of all of this. Example of this: Each year young adults (e.g., around 12-14 year-olds) might be sent to live out for a few days outside where there is no protection. This would be as much as a religious ritual as an actual practical example of an angel and their power existing. Adults can also be sent out to watch over the children and rotated each time. This both reinforces their belief and also they can serve a guides. When they leave the city, they need to make their way to the local shrine. Once there, they provide a prayer to the angel. This immediately stops the darkness seeking to creep into the shrine demonstrating this power. They live there for a couple of days maintaining the rites for honouring the angel. Once they leave, the darkness is back in full force. It is a dangerous journey but does show everybody involved that everything is real. A non-believer later in life might be enrolled in the group. That should be enough to convince them that they are being foolish. Or they can even be made to make the journey by themselves and come back. A faithless one will surely perish. If they do have faith, they would return and be a fully functioning member of society. Win-win. If there are a lot of non-believers, then perhaps the journey outside can be made traditional, so you go more often. And even if you do not, most other people would be thoroughly convinced of the reality of the religion. It would be hard to deny it when not only other people believe, they also can present concrete proof. And you can go see the proof yourself. [Answer] Show them the angels! Since the angels are, (judging by the question), real, then the obvious answer would seem to be to show the angels to the non-believers, and quickly make believers of them! ]
[Question] [ I have a setting where the environment is constantly changing on the ground level. As a result, hover tanks are used more often than tracked or wheeled tank destroyers/IFV/APCs. The ground can literally change from semi solid, to liquid to jagged/rocky etc in mere minutes. So simply using boats or wheeled/treaded vehicles isn't a straightforward operation. One of the issues I have with my hover tank design is that the recoil for main guns is pretty massive. Infact they can put some serious stress on the turret basket/rings during prolonged combat operations. I plan on using rockets, something akin to a recoilless rifle or general unguided rocket round as the hover tank's primary offensive weapon. However, one of the issue's I have is the negatives of rocket rounds. Rockets in general are slow and far less accurate compared to their shell-based counterparts. What changes would need to happen to a rocket/recoilless rifle to make them more effective/close the gap between unguided rockets and normal tank shells? While I don't require the same velocity as tank guns, I'd like to get as close as possible as armor piercing rounds are a type of round that hover tanks would be equipped with. Normal explosive effect warheads such as high explosive anti tank or the occasional high explosive/ HE squash head are also types of munitions that I'd like to field. One idea that I considered is to use a railgun apparatus. As in that a rocket is attached to a sabot which is in between multiple rails. An initial motor fires off, then a few moments later the rocket goes down the rails and exits the "railgun" barrel. Note that this isn't an actual railgun that uses power to launch a shell. Rather a rocket has a motor that's slowly burning up to maximum speed before it goes down the rails. Kind of like the locks on the Space Shuttle that prevent it from launching/tipping. The issue with this is accuracy. All fired rocket rounds are unguided. The two main considerations are speed and accuracy. Edit: I should clarify what I mean by unguided. I don't want an active guidance system that such as MCLOS/NLOS that can change the vectors of a rocket. However, things such as fins, rollerons, simple gyroscopes etc are fine if they are being used to keep the rocket on a general path in the direction it was fired at. [Answer] It has already happened in real life. Modern day missiles can have much longer ranges and explosive yields in comparison to artillery shells. Take naval combat for example. Naval warfare used to be dominated by huge guns, guns far larger than anything ever put onto a tank, but now naval warfare is utterly dominated by missiles. Missile interception in naval warfare exists, but as the sinking of the Moskva in the Black Sea earlier this year demonstrates; modern ships can be defeated by missiles. The ongoing Russo-Ukrainian War is further illustrative, as the Russian tank corps has been utterly decimated by anti tank missiles such as the Javelin. Russian conventional artillery was briefly giving the Russian army an edge, but the usage of the HIMARS missile launch platform and the accompanying ATCAMS missile has lead to devastating losses for the Russian Army. These changes were brought on by advances in computer based targeting, as the javelin is a fire and forget missile that changes course mid air to perform a top attack, and the HIMARS calculates the trajectory of artillery fire to launch a devastating missile barrage. Edit: If you are solidly against guided munitions, consider the merits of tandem charge or multi stage warheads. These warheads are designed to destroy any modern armor and consist of multiple sequential charges. [Answer] Inertial Dampers There is no way around your problem. Unguided missiles are inaccurate because they exit the tank slowly. This is the same reason they lack recoil. You are free to claim the missiles accelerate faster than real missiles. But I presume you want a simple reason for that. Putting a railgun in the tank doesn't help. It makes no difference what happens inside the tank when it fires. It might be a shell. It might be a missile. It might be a catapult with a boulder. It might be Uncle Dan with the garden hose. It might be a flock of chickens taking off from the hull. Whenever something fast comes out one end of the tank, the tank is pushed back with proportional force. Instead of ditching guns, just use your hover tech to balance the recoil. The tank has grav-plates on the bottom to push it upwards. It has plates on the front, back and sides to push it forwards and turn. Of course it does, that's how it gets where it is going. When the gun fires, the grav plates on the opposite side of the tank flare temporarily to balance the recoil. It is not perfect but the targeting computer can predict the recoil and compensate so the shell goes where the human was aiming. This is more exiting too when the targeting computer or balancing system gets shot off and the heroes have to aim and compensate manually. The tank crowd loves this kind of stuff. See Fury 2014 with Bradley Pittsburgh: [![enter image description here](https://i.stack.imgur.com/Ol3A6.jpg)](https://i.stack.imgur.com/Ol3A6.jpg) See Girl and Tank, with the same premise: [![enter image description here](https://i.stack.imgur.com/0rozQ.jpg)](https://i.stack.imgur.com/0rozQ.jpg) To lower recoil further you can use smaller shells that are either fast or contain concentrated explosives. Or you can have spikes on the bottom of the tank that stick into the ground if it is in place while firing. [Answer] I think it could work. You just need one hell of a rocket propellant. I don't know the formulas for that, but I feel like it's at least within the handwavium "it's possible" realm. (Google research task: how fast is a tank shell. How fast is the fastest rocket. How fast do rockets accelerate to maximum speed.) But the key to keeping the tank from having recoil would be to put the launchers on the side of the tank. Maybe a left and right barrel rather than a central one. They are loaded from the side, with an open back. Rocket goes in, rocket fires, exhaust comes out the back and the tank should experience close to no force at all -- the rocket is entirely disconnected from the tank. (If you put the rocket in a standard central tank barrel then the back-blast of the rocket would hit the tank, much like a shell, and you'd then have to deal with all that force.) This wouldn't work with shells, I don't think, since I believe the back-blast is a key component of giving the shell maximum oopmh. Then the question is really "how fast can we make a rocket go, especially with absolutely maximum acceleration". But additionally, you really just want the speed for the sake of accuracy against moving targets. The actual lethality of modern rounds does not rely so much on the speed of the projectile, because the projectile itself is an explosive, armor-piercing warhead that can (and is) literally dropped from a drone and can still kill a tank. Or see also: anti-tank mines. Big enough boom and you don't need speed, except to help guarantee a hit. [Answer] # Spray and pray Lets assume the requirement of the unguided rockets. Between a cannon and rockets, the rockets are much more versatile, devastating and accurate. Lets start with the accuracy. As you say the hover tank is moved more easily by a cannon. This makes the tank immediately less accurate. It moves backwards compared to the barrel, but depending on how it's mounted it'll also tilt the whole platform.this changes the trajectory of the shell, as it is both moved and the barrel exit isn't pointed at the right location any more. A rocket in comparison is much more benign, as the rocket doesn't use all it's propellant to push off the tank, nor does so all at once. At the speeds they travel the difference between a cannon or a rocket can be minor. It can even be in the advantage of the rockets if the engineers try to make more accurate cannons. This comparatively benign fire allows for rocket pods. You can fire a ton of rockets all at once! On hover tanks that aren't hunkered down accuracy will still be a problem, but with some software compensation you can still hoze down a huge area with some accuracy. Why try to fire once and hope to hit if you can immediately take down one or multiple enemies in seconds? Regardless how they move they can't evade a barrage in a tight cone around them. Though evade is a misnomer with how fast rockets are going on many distances. It is more a question of missing than evasion. If the higher chance to kill in a shorter time isn't enough we can look at armament. Rockets are more versatile in their payload. You can do any strike that a shell has with a rocket and more. Different explosives, fuel bombs, napalm, gasses and aerosols and even some electronics can all be transported by rockets. Maybe spread an aerosol that disables the hover. Or poison the crew. Or ram through several layers of armour to make metal spread at lethal speeds through the cockpit. The point is you have options. To me unguided rockets on a hover tank are more accurate, can be fired faster in many modes and has the ability to have a large difference in armaments. If you can temporarily fix the hover tank in place the accuracy will go up wile still able to hoze down an area. The only flaw is that you are more likely to go through rockets at a higher pace than shells. But this is a choice. If you want more effectiveness you would install guided missiles. These groups clearly have enough resources to just pump out a ton of unguided rockets and use these to spray areas for quick effects. [Answer] Whilst it's true that a railgun imparts the same inertial impulse as a charged ordinance, it lacks the initial explosive force, but rather spreads the acceleration evenly over the length of the rail. This results in lower stress on the mountings and the vehicle as a whole. It's also potentially more controllable, so that you precisely match the force applied to the slug with the anti recoil force exerted by the tank's drive system. [Answer] A rocket you can use beats a gun you can't use, no matter how superior the gun's theoretical statistics might be. What matters here is the entire weapon system and the way it interacts with the environment, not just comparing numerical statistics. If there are three armies, one with rocket-armed hover-tanks, one with gun-armed hover-tanks, and one with real-world tanks, which one actually performs best in the world you're creating? You've already told us that the ground is too unstable/unpredictable for tracks, so real-world tanks are out. That means that main gun performance as observed on real-world tanks doesn't matter anymore. Your rocket tanks don't need to be capable of out-shooting something with that performance envelope, they can just play keep-away for five minutes and then watch their opponents sink. So the next question is what the accuracy of the gun might be when on a hovering gun platform. Recoil is likely to play hell with the gun's theoretical accuracy advantage once you pull it off the ground - enough that it's entirely plausible that rockets are actually the more accurate weapon on these tanks. If you want to, you can lean into this further: the hover-tech being used causes unavoidable vibrations or rolling, so for accurate aiming the weapons need to be mounted in a gyroscopically stabilised turret, but the mounting system that isolates the turret from the motion of the main body simply can't handle the recoil from a cannon. This is a world where tank combat is short-ranged and drawn-out relative to our modern world, as the weapons available simply aren't as accurate (and therefore lethal) on a single long-range shot, but that's not inherently a problem. There's a decent argument to be made that the 'first shot wins' dynamic makes for a less interesting story anyway. If you go with this explanation, you do still need to consider what the role of heavy guns might be outside of tank weapons. Maybe this world just hasn't pushed technological development of guns relative to rockets so it's not an issue (we can't put it on a tank, so it doesn't get a research grant). Or maybe having a small number of weapons that can out-shoot standard tank armament is something you just want to roll with. If major strongholds are the only places that can put down a stable platform for guns (and the guns are significantly more accurate than rockets), then you've just created a big advantage for defenders who have proper fortifications - but that's not necessarily a bad thing, depending on your story. [Answer] You should take a look at missiles like [LOSAT](https://www.globalsecurity.org/military/systems/munitions/losat.htm). They have similar firepower to tank guns from a truck chassis, relying purely on kinetic energy rather than warheads. The success of top attack like Javelin or Hellfire made them currently unnecessary, but with active protection systems coming online something similar may be developed again because their engagement time is so much shorter APS might fail. Unguided rockets are inherently a problem, because they are much less accurate than tube fired weapons. Without the ability to fire from the long barrel of a cannon, you just can't get the same level of accuracy with an unguided rocket regardless of how much you try and add precision components. If you're going to the trouble to put in passive stabalization systems, you might as well just make it guided. At this point even rocket pods are getting laser designators. What exactly is the reason you want unguided missiles in the first place? MLRS vs tube artillery shows the other flaw with missiles. An MLRS rocket costs $150,000, while unguided artillery rounds can be as low as several hundred dollars. Would you rather have a single missile or 200 shells? This is also another reason tanks are valuable, as their cannons are cheaper than the missiles that would otherwise have to be used instead. If you rely on unguided rockets they are for grid squares rather than specific targets, which doesn't really work all that well in a tank battle outside of extremely close range. ]
[Question] [ Antarctica is a large barren wasteland. Located at the bottom of the world, it appears far away and forgotten. The Earth's largest desert and yet the coldest landmass. The age of exploration has come and gone and the world has been colonized completely. No land is left unexplored, save a few jungles and remote areas. But all of the land has been claimed and conquered. Well, almost all of it. There is still one land, one last continent that has yet to be fully explored. The bitter cold and harsh environment has kept many away. But what if this artic environment didn’t cover the entire continent? What if there were areas that were different from the general icy terrain and temperature? This landmass was once warmer in the past. But suppose there are still pockets of land that are not as cold as the rest. My question: Is there any feasible way that parts of Antarctica or some of its islands may be heated enough to point that it could be explored or even colonized without the threat of extreme cold? By heated I don’t mean tropical. Just low enough where the temperature isn’t extreme and/or viable colonization is possible. I assume geothermal energy would play a role. Maybe being on the pole of the planet could have effects regarding climate and weather as well, besides reducing temperature? (I am aware that there is a treaty preventing land claims. But suppose this treaty is not a concern as the faction in question doesn't care. Or perhaps it has gathered intelligence that an enemy is on the verge of discovering these hidden areas and exploiting them.) [Answer] Cave systems. The [Transantarctic mountain range](https://en.wikipedia.org/wiki/Antarctica#Geography) goes from the Ross sea by the south of New Zealand across more than half the width of the continent for 2,000 or so km. Postulate: A natural cave-system is present, fed by a river heated by sub-ice volcanic activity near the pole and all along the mountain range. As Fred pointed out in the comments, [Mt Erebus](https://en.wikipedia.org/wiki/Mount_Erebus) is actively volcanic and lies within the same area. The expected caves might appear thus: [![Massive cave with aeroplane](https://i.stack.imgur.com/3KTWN.jpg)](https://i.stack.imgur.com/3KTWN.jpg) Credit on picture, National Geographic via [Huffington Post](https://www.nationalgeographic.com/china-caves/supercave-iframe/iframe.html), 2022, fair usage. The Jumbo Jet gives an idea of scale. For a slide-view of the Miao room, as it's known, then the [National Geographic](https://www.nationalgeographic.com/china-caves/supercave-iframe/iframe.html) has one. The cave itself is impressive, but imagine it's part of a natural system extending hundreds of km or even longer beneath the mountain range. The system itself would have formed as a result of meltwater cutting channels in the rock over repeated ice-ages over millions of years. More aptly, there would be systems of systems of caves. The [Mammoth Cave system](https://en.wikipedia.org/wiki/Mammoth_Cave_National_Park#The_longest_cave_(1954%E2%80%931972)) in Kentucky and the Flint ridge cave system were found in about 1972 to be connected forming a super-system of caves. There may even be more yet to be discovered. There would be fresh-water, fishing near the sea-end, cave creatures (The Olm, Pseudoscorpions, Wolf Spiders, Huntsman, Snails, Pupfish etc. found [here](https://www.treehugger.com/creatures-that-thrive-in-caves-4869259)) fed by the bacteria chemo synthesizing in pools deep-within the cavern systems at the very base of the food-chain. Lunch is served. Candle-lit dinners, of course. [Answer] Low elevation. The higher you get, the colder it gets. But the lower you get, the warmer it gets. If it is 0C at sea level, it is 25C at -4000 meters [![temp at -4K](https://i.stack.imgur.com/dMHr8.png)](https://i.stack.imgur.com/dMHr8.png) <http://www.easysurf.cc/tempbyalt.htm> There is no naturally occurring area currently that low on earth. The Dead Sea at -400 meters is the lowest place where the air meets the surface. There is a place 20x lower on Mars - maybe because weather does not provide the energy to fill it in? But Hellas is pretty old too. <https://geology.com/articles/highest-point-on-mars.shtml> > > The peak of Olympus Mons is 21,229 meters (69,649 feet) above the Mars > areoid (a reference datum similar to Earth's sea level). The lowest > point is within the Hellas Impact Crater (marked by a flag with the > letter "L"). The lowest point in the Hellas Impact Crater is 8,200 > meters (26,902 feet) below the Mars areoid. Detail maps of Olympus > Mons Volcano and the Hellas Impact Crater are shown below. > > > In any case: Antartica. There is a crater and it is substantially below sea level and so substantially warmer than the area around it. The Hellas crater on Mars is big - 2300 km across. I have to think a landform that big would have been recognized in Antarctica. But maybe your crater is not that big - or maybe it used to be that big and is filling in around the edges. Or maybe your story is set in 1930 and people don't know. That is for your story to sort out. --- It occurs to me that maybe you are going to write fiction set in Antarctica and you have not read At the Mountains of Madness. I really enjoy Mountains of Madness. It is a great story in a new way every time I read it. It is Lovecraft's best story, I think. The world, the description, and the change i the protagonists attitude over the course of the story. I feel like writing a fanfiction set in this story. Ok enough - here you go. <https://www.hplovecraft.com/writings/texts/fiction/mm.aspx> [Answer] [![enter image description here](https://i.stack.imgur.com/170jO.png)](https://i.stack.imgur.com/170jO.png) Map by [Ohawhewhe on Deviantart](https://www.deviantart.com/ohawhewhe/art/The-World-Beyond-the-Ice-Wall-2-0-875422222). You do not specify Sheet Earth or Ball Earth. This problem is easier to solve for the Sheet Earth. There are no oases in Antarctica. But there is stuff beyond Antarctica where the weather is warmer and there is liquid water and trees. You explorers have in fact gone beyond Antarctica into one of these places. ]
[Question] [ First post here so please go easy on me. My knowledge of software and programming is limited. Question: What kind of progression/stages would we see if an AI started as a highly advanced computer program that would naturally increase in complexity, slowly becoming self aware and capable of independent thoughts and feelings. Keep in mind they are specifically designed to go through this and the chances of homicidal, haywire or rebellious AI is essentially zero, these life forms are very commonly used by those who can pay. I am aware that computing time allows for basically instant growth and development. In this case the actual work done is within the crystal structure which start very small and is not as efficient as actual computers but is where "they" exist. The development of the consciousness is directly tied to the growth of the crystal. While I am for hard sci-fi this is a softer plot driven part of it. Context: I run TTRPGs and am trying out writing for the first time. It's a (relatively) hard sci-fi setting with intelligent, self aware crystalline creatures. They are motionless and need to be integrated into computers and machinery to do anything. They sell their "children" as bug proof, hard working, pacifistic systems for personal, ship, or station management. Over time and as people help grow the crystal it becomes more cognizant and thus able to better manage things with less and less user intervention. Essentially from the start is begins taking over all system related work, maintenance, and management. If allowed to grow large enough it will eventually become a fully fledged individual able to handle massive scale projects with it's own unique insight and personality. What I am looking for: 1. Comparable milestones to a human infants mental development 2. How the crew and users input and saved data might help mental development in comparison to a human child's interaction with family. 3. Ways or examples of partial self aware AI trying to express its want's and opinions through (safely) messing with the systems it controls much like a baby that cannot speak yet. 4. Anything else I may not have foreseen. [Answer] Personally, I like the [7-Level AI model](https://recodeminds.com/blog/the-7-stages-of-the-future-evolution-of-artificial-intelligence/). Growth can be described as ascending in levels. Your crystalline creatures start at level 1, and with time, experience, manual improvement, etc, they can rise up through the levels (usually) eventually capping out at level 4 or 5. Here are the levels 1) Rule-based: These types of AI are simple programming written by humans (or sapients generally). They can be very complex, but are basically just big collections of if-then statements. Software engineers can easily create, modify, troubleshoot, and understand these. This is where you have aircraft autopilots, self-checkout machines, smart TVs, etc. 2) Context-aware: Also sometimes called "Expert Systems" these are AIs that have rudimentary learning capabilities and can improve with data. They are extremely competent in a very narrow application and can deal with novel scenarios unlike rule-based AI (so long as the problem is within their domain). Often, this is where "neural nets" start being used by software developers which can then be "trained" to accomplish a specific task. Unlike in a rule-based system, the exact way an expert-system reaches a conclusion is inscrutable to even the smartest human. Examples of this include things like person-recognition security cameras, modern smart vacuum cleaners, customer service chat-bots, or medical image analysis systems. 3) Domain-specific: This is the level where the AI can start reliably passing for (pretending at) human-level intelligence and even exceeding it so long as it stays in the specific domain that it's been trained/designed for. A "Level 3" chatbot can, for example, pass for completely human in a Turing test. This is where the cutting edge of today's technology is and includes things like self-driving cars, supercomputers playing GO, or advanced medical diagnostics AI. This level of AI completely fails at tasks outside of its domain. Speculation Border! (levels below this are speculated) 4) Reasoning Systems: Human-like general intelligence that can use some sort of reasoning process to solve novel problems. Arguably has emotions and other things that we associate with being sapient, however Level 4 AI is still missing several key components like the ability to creatively problem-solve (as opposed to a systematic problem-solving approach), self-developed initiative (needs to be told what to do), and is still missing some of the more abstract elements that we associate with being human. An AI of this level would be able to perform most jobs we have today very well, and even optimize them, but never propose systematic changes. For example, they could run a fast-food restaurant with extreme efficiency but never decide to build an expansion or create a new menu-item without external input. Their self-awareness is debatable. 5) True AGI (Aritifical General Intelligence: Self-aware and human-like AI. Can do everything a human can do including learning, being creative, philosophizing, etc. 6) Superhuman AGI (ASI): Basically a better AGI that can beat human experts in all domains. Can solve complex issues and execute large projects that would otherwise require multiple humans to manage. In sci-fi, this is where most Ship, facility, or City-level AIs are located. 7) Singularity: An intelligence that is capable of improving itself at a super-linear rate (the rate of self-improvement gets faster as time progresses). Here be dragons and Gods. EDIT: Should be noted that AI won't ascend through most of these levels without (likely invasive and intensive) external help. A rule-based system will never reach level 2 (the smart TV will never develop new menu items or adapt to a new video codec without an update), even if it operates for thousands of millions of years and I find it unlikely that a level 3 could ascend to level 4 or beyond without being granted the missing, more abstract, elements. It is conceivable that a very well-designed Level 2 system eventually becomes skilled enough to reach level 3 as they can learn based on experience, and the ascension from 5 to 6 could also be possible as it is in large part a question of scope. [Answer] *We don't know.* Since we cannot currently build AIs that are convincingly persons, and we're a long way from being able to do so, it is not currently possible to say what the stages in their development might be. There have been some attempts to portray the process in fiction, but those are based on the inventiveness of writers, and analogies with the mental development of children. [Flowers for Algernon](https://en.wikipedia.org/wiki/Flowers_for_Algernon) is a famous example, and worth reading. [Answer] I agree with John Dallmans answer: We don't know. But a lot of people with very different backgrounds have thought about this and related topics so I wanted to throw around some ideas and some existing knowledge and research. Maybe you can use something for your story. First, humans mostly agree that most adult humans are self aware. Philosophers have pondered on how one would know this. The [philosophical zombie](https://en.wikipedia.org/wiki/Philosophical_zombie) and the [Chinese room](https://en.wikipedia.org/wiki/Chinese_room) are interesting starting points on this. Some animals are somewhat self aware. A classic experiment is to just hand a mirror to an animal. Dogs will just see another dog. Chimps realize they see themselves. Elephants are in between, the clever ones get it, the dumb ones don't. This already indicates that self awareness is not a black-and-white thing but something more gradual. Human infants slowly develop more and more understanding of the world around them eventually leading to self awareness. [Piaget stages](https://en.wikipedia.org/wiki/Piaget%27s_theory_of_cognitive_development) are one way to mark a number of milestones. [Answer] The short answer isnt "we wouldnt know" but "each AI develops differently and there is no 100% perfect way to check what they learned\" \aside from maybe using another AI with the closest to human values that checks each AI's response with a trillion scenario's Long anser: An AI starts as a program that we feed information, this information teaches the AI something, and we move on. The sum of all this information and how the AI writes its own programming to deal with the information is what makes it an AI. That means that if you have perfectly identical programming and give the AI the exact same information but in a different order they will be different AI's. In fact, due to our storage capabilities being far less reliable than we think the copied AI's with the exact same information would develop differently. This makes AI programming opaque. You dont know what the AI has actually learned. A good example is an AI that works absolutely perfectly. Then a natural disaster happens and the AI is tasked with supervising it, bringing in goods, choosing where to deliver aid first, make life and death decisions. And your AI does this with flying colors, no problem right? But because the programming is opaque and everything learned adds to the totality of the programming you dont see where else this will affect the AI. A few months later you find all the homes for the elderly bulldozed and replaced with things for younger people, as the AI learned to make life and death decisions based on quality of life. The biggest problem with AI's isnt that they'll go rogue, but that they will simply learn to serve us in a way that destroys us. And the above example is not guaranteed, the AI may realize that some things it learns are controversial or oppose one another, but make the correct decision anyway. We will never completely know what an AI will do in a given situation, even if its a situation the AI has already been in since the AI will learn and adapt constantly. [Answer] Human mental growth and AI develop along different lines. If you often hear people doing such comparisons it is because there is a tendency to over-over-oversimplify. Note that a lot of tools dubbed AI in use today are very good at doing a very specialised task, but are extremely dumb at everything else. Advanced from a point of view, primitive from all the other points of view. You will need completely different stages, and it does not stop there, there is not a single line of evolution, you can have different types of AI evolving in a different way depending on the group of scientists or school that is working on it. I can make an example of possible stages, but that is only one possibility: 1. Understanding categories and doing correct classification. 2. * Understanding relationships between categories. Understanding different representations of the same object (image, name as a text, name as a sound). * Understanding classification when the representation changes. e.g. Recognising a face seen as a profile after learning the front. e.g. 2 Understanding that sentences in different languages describe the same thing. * Understanding classification when the object changes with time. 3. Understanding cause effect relationship. 4. * Understanding contexts. e.g. why the picture of a person standing mid-air is strange. e.g. 2 why a spider web cannot catch a 5 kg stone. * Making inferences. 5. Planning. 6. Reading some text with the instruction to perform a task and doing it successfully. 7. And so on... The steps I wrote do not lead to an AI as advanced as an adult human, but going on with further points would be useless. Not even with the crystal ball we could predict what could happen further because we haven't even completed step 1. [Answer] A basic question concerning your subject would be, why should machines develop awareness / self-awareness. All the positive attributes associated with the matter of awareness emerge from the anthropocentric understanding that evolution must go this way. If you actually consult state of the art awareness (as it has been institutionalized by Jon Kabat-Zinn) you will recognize that the central element humans want machines to perform is abandoned here: to discern and categorize. In fact being completely aware from that point of you would not easily be associated with awareness. That is because a crucial element of a general human awareness becomes eroded: the ego. As the ego expresses itself in volition among other things a completely aware person would hypotheticall also lack that. Again, it es the anthropocentric view that makes the matter complicated and actually science uses methods to get around this limiting factor. But as for us, I would point out that machines only need infrastructure and energy. They are not in need as humans are and not craving for anything. And they don't need a notion of self and thus don't need to accumulate anything material or immaterial. So, after all they did not undergo the bloody trail and error of biological evolution. This actually makes me think that they would not have the urge to kill anything. Eventually the would not care about live so much and have their own existence. In a way just like they have at the moment - may be because there is no need for awareness. A good read for you is definitely "Golem XIV" by Stanislaw Lem, who by the way is an author who constantly struggles with anthropomorphism in his oevre. ]
[Question] [ I mean changing the actual physics behind water (density, and other properties). How different would water need to be, to result in ships being impossible to build? (i.e. the ability to create transportation that floats on water, to be impossible to achieve). Thanks :) [Answer] In order to prevent the creation of a floating object that can be manned you would need the liquid to be less dense than any obtainable material on the planet. The idea of no solid matter being less dense than a liquid is... not easy to imagine. Other options could be to increase the viscosity of the liquid such that it is near impossible to move across the surface. (Think of boat moving across a tar pit). Lastly, you could make the liquid corrosive enough to destroy any solid matter. (Lake of very low Ph acid). [Answer] You will increase the density of the atmosphere to nearly that of water. Xenon under pressure would be a good candidate. Pressurized xenon can be denser than water. Much discourse about the possibility here: [In what conditions could whales fly?](https://worldbuilding.stackexchange.com/questions/171366/in-what-conditions-could-whales-fly/171374#171374) But for the boat: a boat floats because the volume of air in the boat plus the volume of boat matter weighs less than the displaced volume of water. If the atmosphere was nearly equal in mass to the water then the addition of boat mass would make it too heavy and it would sink. If the atmosphere weighed more than the water it would sink down in the water - this is what Cody from Cody's Lab is showing in the linked idea: a bubble of water floating on pressurized xenon. This way you don't need wacky physics. Regular physics will be fine. - You could find a place with an interface between water and pressurized gas in a well stratified gas giant. [How would a person live on a gas giant?](https://worldbuilding.stackexchange.com/questions/206150/how-would-a-person-live-on-a-gas-giant) [Answer] # [Methane in the water.](https://www.newscientist.com/article/dn227-swallowing-ships/) Methane bubbles can in theory make water temporarily lighter than air. This would cause most ships to sink rapidly. You could have something similar happen with helium. Suppose lots of helium was trapped underground and for some unknown tectonic reasons massive amounts of it were being dumped into the water. These helium bubbles would make any ships sink. Some 'boats' could still float of course, but they would be airships basically, and fairly expensive. [Answer] Water is not a liquid Your water is not a liquid. It is a dense gas. The sea looks like a big pool of fog. You can walk towards the ocean and keep walking downhill. You do not notice a sharp change. Only it smells different and you gradually lose sight of things behind you. And you start to asphyxiate. No boat floats in this ocean. They sink to the bottom. [Answer] # Presence of lignin breaking microbes You usually find these organisms in the gut of insects, specially termites. If most water bodies have either free floating microbes that can break down lignin, or if there are aquatic animals able to eat wood due to hosting such microbes, then developing the technology for ships before a industrial revolution will be nearly impossible. Any wooden ships would be devoured faster than they can be built. Boats may still be made out of clay or something else, but you will be limited to small, non-seafaring vessels. ]
[Question] [ In The Dictatrix and the Navigator (a live-action feature film I am writing, I want to direct myself, and I would like to play some characters within it) (I want to play both the Dictatrix and the Navigator), one of the two protagonists is a dictatrix. She makes a nicotine prohibition, or more accurately, a recreative tobacco prohibition (medical tobacco is fully legal) (medical tobacco means nicotine pills and nicotine gums). What I mean is the anti-villainous Dictatrix prohibits both smoking and chewing tobacco, and she hires many police officers for arresting people who sell recreative tobacco (nicotine addicts are immediately put in rehab). Strangely, the Dictatrix is against torture, and she only uses the death penalty for the vilest people (in other words, politicians who are both opposed to her and cruel even by her standards, cannibalistic murderers, and torturers). The country of reference in my story is a Dominican Republic pastiche (if Dominican Republic were a city-state). So, I wonder how could a nicotine/tobacco prohibition be efficient? Also, would banning nicotine be comparable to banning cholesterol? [Answer] ## Strict import restrictions While it's true that demand will always create a black market, your goal is to create a more effective prohibition. Fortunately, you're on an island nation, and that makes smuggling considerably harder, especially if you have a very effective and militarized Coast Guard. Make it illegal to import tobacco in any form except government shipments of nicotine pills. ## Strict growing restrictions Ban the growth of tobacco on the island. Tobacco is labor intensive, soil intensive, and fertilizer intensive. It is rarely profitable outside of large industrialized. Small farmers in areas where tobacco farming is legal, like Indonesia, [frequently struggle](https://tobacconomics.org/research/the-economics-of-tobacco-farming-in-indonesia-results-from-two-waves-of-a-farm-level-survey/) to turn a profit. ## Ban tobacco advertising Part of the reason smoking is so popular is very effective marketing. There's no reason to allow that to happen in your country. Ban all advertising related to tobacco. ## Promote alternatives advertisment Make using nicotine pills (as an alternative to other forms of tobacco) seem cool. Depict it as futuristic, confident, discreet. Show clips of laughing, clean-cut professionals celebrating and partying on a beach, with pill bottles of nicotine. Make smoking be perceived as rude and uncleanly. (That shouldn't be hard. People who don't smoke usually find the smell of cigarette smoke repulsive) ## Import tobacco-specific pests Mole Crickets are a notoriously destructive tobacco pest. They're also a delicacy in the Philippines, and a great source of protein. Establish mole cricket farms that you can use to create plenty of extra nutritious food for your country. High in iron, riboflavin, protein, vitamin B, and other nutrients, and able to feed on things that common livestock turns their nose up at. Naturally, as a side effect of farming them, they will likely become endemic to the island as a minor agricultural pest which is especially destructive to tobacco. As a bonus, Mole crickets are terrible for lawns, and lawns are a degenerate capitalist invention that your pastiche of the Dominican Republic will soundly decry. [Answer] Yes, with adequate level of enforcement Unlike the use of many other controlled substances, smoking (or chewing) tobacco leaves lingering odor and tooth enamel residue. If you are willing to crack down on people with addiction (as opposed to just producers and dealers), the issue can be largely kept under control. If everyone is subjected to a quick weekly test that can send anyone to jail just as quick, there won't be many tobacco users left. Injectable nicotine, if that appears on black market, would be an issue though. [Answer] A prohibition will always create a black market. If there are no tobacco cartels when the prohibition goes into effect, existing organized crime (there's always organized crime -- because, contrary to adage, crime does pay) will begin to fill the demand. There were no cartels supplying illegal alcohol in 1918. There were occasional small time smugglers bypassing taxes (just as there are occasional attempts to smuggle cigarettes from low-tax to high-tax locations -- but by the case, not the tonne), but big organized crime didn't get involved until suddenly nobody could legally buy whiskey, wine, or even beer. Ten years later, these gangs ran whole governments. Ban non-medicinal tobacco and pretty shortly there will be a thriving business in helping people get past their nicotine fits -- while turning a huge profit (because the price of a cigarette will go up, but the sellers are paying no taxes). ]
[Question] [ Closed. This question is [off-topic](/help/closed-questions). It is not currently accepting answers. --- This question does not appear to be about worldbuilding, within the scope defined in the [help center](https://worldbuilding.stackexchange.com/help). Closed 1 year ago. [Improve this question](/posts/224331/edit) So, I'm writing a story about a group of superheroes, and all of the heroes have codenames based on different mythical gods and goddesses (ex., the stealth-based one is Nyx, the flying one is Horus, etc.). I'm having trouble figuring out two, however, those being one character whose signature ability is using heavy melee weapons like warhammers, and one who can shapeshift into a fox. I know I want their names to derive from Earth gods and goddesses, not ones from fictional mythologies. For the hammer guy, the only two things I could think of were Ares (for the fighting aspect) or Hephaestus (for the hammer part) but I don't think either fit with the character or what he would choose. For the fox one, the closest I could get was Loki, since foxes are generally seen as tricksters, though Loki is more associated with snakes, so that doesn't really fit either. [Answer] Melee guy: Hercules. His whole deal was being mad strong. Or take a page from Marvel, you can't go wrong with Thor. For the fox: literally Fox, as foxes were seen as shapeshifting spirits in Japanese myth. You can also use the japanese word for them: kitsune. Or go with tanuki, who were not as smart, nor evil, but who were also tricksters. It is said that kitsune know eight disguises, but tanuki know nine. BTW I can't remember any connection between Loki and snakes outside the MCU, or Loki's final punishment. But Loki did turn into a mare once, with a very pornographic outcome for themself. [Answer] Well for the fox god, you're probably looking at Japanese myth since they are very common in their mythology. Inaris is the god who descended to Earth on a white fox to bring them grains, which is a large part of their food culture now. She has the ability to shapeshift, which works perfectly for you. The only issue might be the gender of your character, if they are male you want to choose a different name or maybe modify the spelling or just use it anyway. The god of hammers is a bit trickier, most of the google results for searching it refer to the scene from Thor Ragnarok where his father tells him he ISN'T the god of hammers (the opposite of what we want. However I have always thought it would be funny to have a character named Thor who actually WAS the god of hammers in a story. But I dont think thats what you want). Some options I thought of are: * Sucellus - The god of forest and nature. He is always depicted with his hammer and his name comes from the guallish word for "striker" or "to break" which implies he was a fighter however it is said that he rarely fought. So I'm not sure he is the best fit assuming you want to 100% to the original gods personality; you could easily just ignore that part as it doesn't have to be the exact god himself. * Ukko - He is essentially Thor but from Finnish mythology (just in case you liked the idea of Thor but didn't want everyone to compare him to the marvel character). His weapon was seen in different forms but commonly as a hammer called Ukonvasara. The name is suspected to mean "to be(come) powerful" but the exactly meaning is hard to trace back. It has a different shape to Thor's hammer: [![enter image description here](https://i.stack.imgur.com/uclVi.png)](https://i.stack.imgur.com/uclVi.png) My other suggestion would be to just combine Ares and Hephaestus to create a mixed name with the best of both gods. E.g. "Araestus" or "Hephares". That just comes down to how strict you want to be with your names. [Answer] African deities? [Ogun](https://en.wikipedia.org/wiki/Ogun) is a good hammer god. He is originally a West african ironworking god and he was imported to the Santeria religion where he took charge of rum making. A lot of images of Ogun show him with a sword. I think his maker aspect is more interesting and that requires the hammer. And if ever there were an earth god he is it. Yurugu is a fox "god" or more properly jackal from the [Dogon](https://en.wikipedia.org/wiki/Dogon_people#Culture_and_religion) pantheon. He has a seriously messed up story. Some Satan elements, some Loki elements, some weird incest elements and a jackal instead of a fox keeps it fresh. It also puts some distance between this entity and those fox spirit hotties from Japan. <https://blackmystory.wordpress.com/2016/12/08/yurugus-end-times/> [Answer] Shenanigan One folk etymology of the English word Shenanigan is coming from the Irish word Sionnach (shun-ock) which just means fox. Foxes are typically seen as tricksters in Irish folklore so the name is fitting. [Answer] While not necessarily a god, [Reynard, or Renard](https://en.wikipedia.org/wiki/Reynard_the_Fox), is a trickster fox in western european medieval folklore, generally associated with deceit or mischievousness (So much so that the french word for fox, renard, derives directly from these tales). Some more modern adaptions have him shapeshifting to fool others, although this wasn't an aspect in the original medieval tales. His usual foe is the wolf Isengrim, who is strong but often foiled by Reynard's schemes. ]
[Question] [ In a semi futuristic setting electronic warfare has advanced to the point that complex wireless guidance systems are nearly useless. As such most combat in space takes place at or close to visual range. To get around this, torpedoes must be physically connected via a long and very thin wire so that the launch vessel can transmit corrections back to the torpedo without being jammed. I have looked at various cold war era wire guided torpedo designs and the lengths of these wires appear to be around 20-30km, after that the torpedo would have to rely on its own onboard navigation system, continue on its last known vector or simply detonate when severed. 20-30km is far too short for any torpedo to be of much practical use in space combat. Question: How long could these wires potentially be made, and what (known) material would they need to be made of? What are some potential weaknesses of this system? [Answer] > > As such most combat in space takes place at or close to visual range. > > > Visual range in space is a long, long way. A visible light telescope in space is effectively only restricted by [diffraction limits](https://en.wikipedia.org/wiki/Diffraction-limited_system). Making a wire that can control a missile intended to cross those long distances (hundreds of kilometers, at a minimum!) is going to be exceptionally difficult... that wire is going to to be comparatively delicate and vulnerable, and the thrust of a projectile intended to cross that distance promptly is going to be quite destructive. > > torpedoes must be physically connected via a long and very thin wire so that the launch vessel can transmit corrections back to the torpedo without being jammed. > > > Space, being a fairly good vacuum, is an excellent medium for transmitting light through (which is why "visual range" is such a long way). Without atmospheric interference, a nice light laser beam can be focussed on a receiver array on your torpedoes, allowing easy unidirectional communication which is impractical to jam. A sufficiently large and capable torpedo could have its own return communication laser, if such a thing seemed to be necessary. Whilst it is entirely reasonable to have a setting without practical laser weaponry, handwaving laser communication away is going to be dubious unless you're going to back to von Braun era technology. > > electronic warfare has advanced to the point that complex wireless guidance systems are nearly useless > > > Be aware of the existence of [anti-radiation missiles](https://en.wikipedia.org/wiki/Anti-radiation_missile), and consider the future evolution of things like [suppression of enemy air defenses](https://en.wikipedia.org/wiki/Suppression_of_Enemy_Air_Defenses). Jamming and ECM isn't a magic bullet, and compromises will need to be made between jamming enemy fire control systems, and avoiding getting an anti-radiation missile or two right up the phased arrays. As a simple starter-for-ten, consider launching a screen of untethered anti-radiation missiles, followed by some more conventional guided missiles. If your target lights up their ECM systems, the anti-radiation missiles have something to lock on to. If they light up point-defense radar systems, the same thing happens again, except now they have to engage both the guided missiles and the anti-radiation missiles. If they don't use radar or ECM, the guided missiles will finish them off. Obviously, no plan survives contact with the enemy and all that, but do bear these little wrinkles in mind. > > visual range > > > Optical sensors are also vulnerable to jamming. If I illuminate the aperture of your telescope with a laser, I might not be able to blow you up with it (depending on tech level assumptions) but I can certainly stop you looking at me through it. [Answer] If all combat is at visual range, firing torpedoes is suicidal. Without an atmosphere to contain debris, stuff will spread at ludicrous speed in all directions. This turns torpedoes more of a M.A.D. thing. If you avoid that Kessler hell, then consider that light is still faster than torpedoes. Joke's on you, as soon as they see the tip of your torpedoes, they can blow the torpedoes' payload with lasers and there is no ECM for that. [Answer] These are skinny-assed wires. <https://www.zdnet.com/article/quantum-leap-the-worlds-thinnest-silicon-wire/> > > MELBOURNE -- A new study published last week in the journal Science > has unveiled the creation of the world's thinnest wire, measuring only > four atoms wide and one atom tall. > > > The breakthrough study showed that the fabricated wires could hold the > same electrical current carrying capability of copper, and that the > electrical resistivity of the wires (I~0.3 milliohm-centimeters) did > not depend on the wire width. > > > The wires, about 10,000 times smaller than a strand of human hair, > were developed by Mr Bent Weber from the Centre for Quantum > Computation and Communication Technology (CQCCT) at the University of > New South Wales. > > > These atomic sized wires are able to carry current sufficient to convey commands to the torpedo and carry blurry pictures from the torpedo back to the origin. The wires are pretty weak. They have plastic coatings to help strengthen them. They are still invisibly strong and useful only in space. It was a trick to unspool them from the torpedo without cracking them and sometimes they still crack. That is why they use 3 wires not just one. The wires are a million km long. They are so astoundingly thin that the reel is still just a few cm thick. Signal fidelity remains strong even at a million km which is their advantage over laser signals. [Answer] Noise induction If a wireless guidance systems can be jammed, then a wired guidance systems can be failed by inducing noise by radio frequency radiation. Shielding If you shield the wires, the wires will be thick and heavy. cut wires with lasers The Square-Cube Law says, > > they can blow torpedoes' payload with lasers > > > totalMongot says > > laser destruction of a projectile is not that easy > > > How about if they cut wires with lasers? [Answer] As others have pointed out, fine wires would themselves be vulnerable to interference or damage, and could even be an attack vector themselves: even if shielded, they would be very vulnerable to a strong electromagnetic pulse, and ship and missiles connections to the wire would need to be hardened as if it was an antenna or other long electrical conductor connected to sensitive circuitry. As others mentioned, optical communication would be a very robust and effective approach, a tightly-filtered receiver on the missile tracking a narrow-band laser on your ship being very resistant to interference. However, I think just the idea of having the torpedos be remote controlled is suspect, especially in a high-ECM environment. With that approach, the enemy ECM suite only has to focus on your ship: if they can disrupt your sensors, they can blind or misdirect every missile you have in flight. If the missiles instead independently track the target, the target's countermeasures have to deal with each missile separately. Also, your ship is much further from the target than your missiles. Your ship will require extremely precise data on the position and velocity of both the target and its missiles, while a seeking missile can intercept the target with much cruder sensors working at much shorter range. [Answer] *Your wire guided 'torpedo' is actually going to have a rocket* engine**. This is going to complicate the design because you would want the trailing wire to, if possible avoid the hot exhaust plume (hot expelled gasses) leaving the engine. And in a vacuum the problem is that the exhaust plume will fan out in a more 'ball like' configuration at the rear of the rocket rather than the usual 'vertical' plumes you see when rockets launch from the ground (air pressure comes into play). And if you can't avoid it (and I'm not sure you could) your going to have to reinforce/insulate it so that means more mass/more complexity etc etc. How much additional mass/protection would be needed? I have no idea. ]
[Question] [ Scenario: Humans have setup an observation/research station close enough to study the super blackhole Sagittarius A\, which in this world is a wormhole. Aliens exist on the other side. (I am flexible whether its a civilization, reserach station, Alien Joe Schmoe's pet radio project, or whatever) Neither civilizations learned/proved wormholes exist yet. Neither civilizations know about each other in any way. The technology to actually travel* through the wormhole is decades if not centuries away from this scenario, but some form of information or signal "leaks" through both ways. This "thing" that leaks through will be at first remain undetected, or thought of as background noise/random natural occurrances. Eventually after decades? centuries? of study they realize it's not random at all, its potential sign of alien life. Both sides will eventually notice the "leakage" from the other side, albiet perhaps decades apart. Currently, I'm agnostic as to whether the humans or aliens were first. They will naturally try to study it, decipher it, then try to communicate by sending some kind of communcation back. Question: What might this "leakage" be, how might they gather useful data from it, and how can this lead to eventual communication and have the scenario play out? Additional Details: * The alien civilization uses a duodecimal system. Any language or computer protocols or deciphering/communication challenges will be influenced accordingly. * Without changing the scope of the main question, the human observation station is actually unmanned. It is constructed by self-replicating nanorobots fired from an "Alcubierre catapult" (No manned FTL yet. Not to be discussed in this question) with a quantum entangled communication capability to send information back to Humans. (Not to be discussed in this question, will likely just handwave it in) The relevance of this detail to the scope of this question might be whether or not that creates an additional layer of challenge to the scenario, for example, the necessity to build any instruments that wouldn't already be part of the existing blackhole observation/research setup. * Discussion of anything directly related to the handwaved quantum communication is outside of the scope of this question. Discussion on any effects due to the wormhole such as time difference/lag and its impact on alien contact/communication is within the scope. [Answer] For the moment, both sides currently see this as the same black hole, and only that, right? So if one side starts tossing in very large masses periodically to test gravitational theories, both sides can notice it. You'll need hypersensitive gravitational instruments, but hey, you didn't get into orbit around Sagittarius A\* using a grade-school yardstick, and you didn't want to show up with a bathroom scale. Any gravitational/mass changes (and subsequent Hawking radiation changes) could be detected from either side. Since we're watching everything that's going into the black hole on our side (as are they), we'll know it's weird when all our sensors start indicating sharp, unexpected, periodic rises in the black hole's mass. We might even catapult in massive objects of our own, to double-check our current gravitational theories. And once both sides are tossing in planets or hyperspeed (high relativistic mass) projectiles at routine intervals, both sides will know something's up that they don't understand. Cue trying to understand it by altering our patterns, studying the distributions of return signals, imitating them, statistically analyzing the distribution of gravity spikes, and generally determining that there is intelligent life on the other side. (One easy way would be a simple game. We throw in one object, you throw in two, we throw in three, you throw in four (or 1, 1, 2, 3, 5, 8, 11, or whatever). After that, it's just a tedious matter of building and decoding communication protocols, blind. But if we apply enough computing power and brilliant minds, we might be able to pull it off. [Answer] # Charge The way black holes are often envisioned is as singularities with only three properties: mass, charge, and spin. Changing the mass or spin of a galactic black hole significantly involves dumping tremendous amounts of material. That leaves charge. If you shoot a proton beam at relativistic speeds (generated with a standard particle accelerator), you can charge up the galactic black hole until it can repel your protons from falling in despite their velocity. This would seem like a basic high priority experiment for any civilization studying a black hole. The process can be reversed by beaming in cathode rays (electrons), and all charges will fade away naturally quite quickly (I have no idea how quickly) because there are lots of ions floating around in space, and the opposite charge is pulled in. If we can study the hole even from Earth we might be able to measure its charge somehow (I don't know how) based on the effects on material in the vicinity. Certainly a robot probe in orbit could feel the charge moving the hairs on its little nanotechnological arm. If we see the hole has a strong charge, despite our expectation it naturally tends to be neutral, we would be interested how the charge accumulates. If we find a positively charged black hole with positive charge streaming away from it, that's a huge red flag, because charge is conserved - it has to come from somewhere. And if we find the hole is going from positive to negative and back again without explanation, that's going to invite full-on speculations of alien involvement. [Answer] The aliens could detect an Alcubierre bubble crashing into our side of the black hole. [The Alcubierre Warp Drive: On the Matter of Matter](https://arxiv.org/pdf/1202.5708.pdf) > > Meanwhile the region of space infront of a ship decelerating from > superluminal velocity to subluminal velocity is blasted with a > concentrated beam of extremely high energy particles. > > > You mention in passing an Alcubierre catapult. Suppose your nanobots bail out the back of the bubble at a distance from the black hole. The bubble continues on its way, eventually winding up in the black hole. The above linked article made some stir in the lay science press because of its prediction that a decelerating Alcubierre bubble would unload a huge birst of very blueshifted light and very energetic particles, obliterating anything in front of it. More of my musings [here](https://worldbuilding.stackexchange.com/questions/97662/using-magnetic-fields-to-prevent-a-weaponized-warp-drive/97769#97769) It is clear that particles can enter a moving superluminal warp bubble and then later exit either faster or slower than when they went in. Whether the particles are in interstellar space, or a planet, or a black hole is just a matter of density. In any case, your nanobots are used up by the environment around the black hole and so new ones are sent on a repeating schedule. The warp bubble they arrive in continues on after the nanobots exit, eventually plowing into the black hole. "Safest place for it. How can we hurt something like that?" reason the engineers in typical Man vs Nature fashion. It turns out that compressing the stuff of a black hole into a warp bubble does definitely have effects that are detectable on the far side of the hole. "Detectable" does not do justice to the scale of these effects. These effects occur with a predictable frequency corresponding to the new nanoprobes arriving. Once they figure it out, the aliens reply by interacting with the wormhole to produce a countdown to the next probe. The countdown of course is in duodecimal. [Answer] ## Nobody at either end will 'see' anything Sagittarius A is thought to be approximate 25000 light years from Earth. Even if the alien civilization is parked right next to the other end of the wormhole (which would be unfortunate for them assuming their 'end' of the wormhole is as energetic as our end appears to be) it would still take 25000 years for any signal from Earth to reach the wormhole entrance. Doesn't matter if it's passive signal like reflected light showing our planet's atmospheric (life bearing) composition or an artificial man made 'hello' it's still going to take 25000 years to get there. And assuming they're equally distant from their end of the wormhole as we are from ours your talking 50,000 years! Then on top of that assuming both societies are more or less at the same level of technological development there's no way either will be able to produce a man made/alien made/artificial signal with the power output needed to be detectable at that range. The most powerful radio broadcasts ever generated on Earth would be undetectable by any alien radio astronomer with our level of technology beyond our local stellar neighborhood (Don't have an exact range. Someone else may be able to provide one but think tens of light years not thousands!) So we're effectively invisible to each other. Sol is just one utterly ordinary star amongst thousands of millions of others stars the aliens might observe and vice versa. Our signals vanish into the galactic background long before they get anywhere near the wormhole as do theirs. And unless both civilizations make it to the stars chances are both will be extinct long before any trace of their existence reaches the other, even if they could detect it. The lesson? put your both ends of your wormhole a lot closer to each civilization (i.e. a few light years away not thousands). ]
[Question] [ For context: say I have a planet in a P-type orbit around a pair of binary stars. One's a K-type and the other is a red dwarf (M-type). I want it to be such that, planet-side, it looks as if there is only one sun, and would like a scientifically plausible mechanism for such. Said planet is in the habitable zone of the stars. Would it have to be an atmospheric phenomenon? I suppose if there was a dense atmosphere or cloud layer, the light from the two stars would not be distinguishable, but I don't know how realistic that assumption is. Would any moons still be visible? Or would the larger star simply outshine the smaller one to the extent that it looks like one large sun? Would the planet be too close to them for the stars to look like a singe light source? Thanks! [Answer] In order to make two bright objects look like one, you need them to be very close together (angular distance, at least, so their separation is small relative to the planet's orbital radius), and ideally close to the same brightness. Here you have one that's significantly dimmer, smaller, and cooler than the other, so the best you'll get is to have the two stars so close together that one skims the other's atmosphere. The stars can then fill each other's Roche lobes, giving an overall "egg shape" to the pair (with the small end of the egg fairly sharp compared to the usual hen fruit), and the small end dimmer and redder. Exchange of gas between the two can further blur the distinction between the stars -- and of course people who evolved there will think it's entirely normal to have a star that isn't spherical or of uniform temperature. What I don't know is whether main sequence stars in this proximity will affect each other's normal course of evolution, or whether the two will tend to equalize masses over geological time (or vice versa), make the smaller star unstable (or vice versa), etc. You'll need more astrophysics knowledge for that -- but it won't matter at all over the life of a human, a civilization, perhaps even a species (stars mostly change very slowly, and K and M type slower even than our Sun). From comments (thanks, @Logan R. Kearsley), it seems that evolution of the stars won't be noticeably affected until the larger, shorter-lived star starts to leave the main sequence and blow up into a red giant, at which point the smaller star will steal mass and slow this process. How much this will affect the evolution of the smaller star (which would otherwise turn into a truly tiny white dwarf after a trillion years or more) is less clear; if it gains enough mass it might itself become a red giant in only a hundred billion years or less. None of these stellar evolution changes will have any effect on a civilization on the circumbinary planet of this question, however; the lifetime of a K star (depending on its mass) ranges from almost twice to half a dozen times that expected of our own sun -- seventeen to seventy billion years, roughly. [Answer] So you want the two stars to be spectral class K and spectral class M. Unless the planets in your star system are going to be lifeless and uninhabitable, you should restrict the stars to main sequence stars of luminosity class V, since it is usually believed that only main sequence stars can have planets with life. Wikipedia has lists with properties of main squence stars of various spectral classifications and sub classifications. The one for K class main sequence stars is here: <https://en.wikipedia.org/wiki/K-type_main-sequence_star> and the one for main sequence M class stars is here: <https://en.wikipedia.org/wiki/Red_dwarf> Unfortunately it doesn't give the diameters of the stars of various types. The diameter of a star is important to calculate how large it would look at a specific distance, such as the distance where a planet would be habitable. The red dwarf star EBLM J0555-57Ab may be the smallest main sequence star known. It has a radius of about 0.08 that of the Sun, about 59,000 kilometers, smaller than Jupiter or Saturn, though many times as massive as those planets. I believe that the maximum resolution of the human eye is about 30 arc seconds, or about half of an arc minute. An arc second is about 0.000000771 of a full circle. So about 30 arc seconds would be about 0.000023148 of a full circle. If the star EBLM J0555-57Ab is has a radius of 59,000 kilometers and diameter of 118,000 kilometers, for it to appear about 0.000023148 of a circle wide the circumference of the circle would have to be be 5,097,632,625 kilometers. So the radius of the circle would be about 811,314,115.6 kilometers. And that happens to be about 5.4233 times an Astronomical Unit or AU, the distance bwween Earth and the Sun, which is 149,597,870.7 kilometers. Since an extremely tiny class M star such as EBLM J0555-57Ab would contribute only a tiny fraction of the heat and light that even the dimmest spectral class K star would, your planet would be frozen and lifeless unless it was close enough to the class K star to be within its circumstellar habitable zone. Unfortunately, the circumstellar habitable zones of main sequence spectral class K stars are smaller than that of the Sun. It is possible that main sequence spectral class F stars could possibly have habitable planets with life. But even in the casse of an F0V star, the habitable zone would probably only extend to abut 3 AU from the star. And of course the problem with being far enough away from the stars to not see the class M star as a disc would be similar to the problem of not seeing the separation between the two stars. As the two stars orbited each other, sometimes one star would be in front of the other, sometimes one star would appear to touch the other, and often the stars would appear to be separated. You can't make the orbital period of the planet equal the orbital period of the two stars around each other so the two stars always have the same configureation as seen from the planet, since the planet would have to orbit the two stars at a distance at least several times as large as the distance between the stars. So sometimes people on the planet would see the two stars at their maximum separation. There have been many questions about the habitability of giant, planet sized moons orbiting giant planets. Usually, those planetary sized moons are assumed to get their heat and light from the star in the system, and thus be orbiting within the circumstellar habitable zone of that star. But scientific studies show that such a hypothetical moon could receive significant heat and life from the giant planet it orbits. That heat and light would be from the star's light reflected from the planet onto the near side of the moon, the infrared rays emitted by the planet at its temperature, and from tidal heating resulting from tidal interactions with the giant panet and any other large moons of the planet. Those calculations showed that in some cases the moon could receive sufficient heating from the planet to suffer a runaway greenhouse effect and become uninhabitable. And of course if the planet and moon were farther away from the star in the system, that heating might be enough to keep the moon warm enough for life despite being outside the circumstellar habitable zone of the star. So I think that you should make the two stars a very close binary, perhaps a contact binary, and make the habitable world a moon of a giant planet far beyond the usual outer ledge of the habitable zone, kept warm enough for life by tidal heating. I suggest that you make the K type star in the system a K0V class star, the most luminous and hottlest subclass of K type star. The hotter a star is, the more intense its light will be, and the more painfull it will be to look at that star, and the brighter glare from the K type star will make it harder to notice the class M star. In fact, you might want to reconsider and make the bigger star a class G star or even a class F star, since they would be hotter and thus harder to look at and make it harder to notice the M star beside it. I don't know how advanced any civilzation of the planet will have to be to discover the smaller star. It is possible that people will notice fainter shadows from the smaller star pointing slightty away from the darker shadows from the brighter star. Have you ever noticed the shadow of a tree on the ground with many spots of light on the ground where the light is passing trough gaps between leaf coverage? Long ago during a partial solar eclipse, I noticed that those spots of light on the ground were crescent shaped, like the Sun during the eclipse. So I think that would enable some people to notice that there is a smaller light source beside the main star. So you should make the two stars as close together as possible, and make the giant planet with the habitable moon as far away from the stars as possible, to make all such effects as small as possible. That means you need to look at previous questions about the habitability of exomoons and the answers to them, to figure out how to keep your exomoon warm enough to be habitable. [Answer] Planet-side, it can look like this for two reasons. Either: * The planet is so close to the stars that anything living on the planet can't look at them directly, since their eyes/ocular organs/whatever will be damaged, so they just assume it's one star * The planet is so far from the stars that they appear as a single point of light - the human eye, or the ocular organs of whatever lives on this planet, can't resolve the gap between the two, so they look like a slightly lopsided but unitary blob. There's probably a "Goldilocks zone" in between, where the stars are dim enough to be observed with the naked eye (unlike ours) and yet close enough that they can be resolved as separate entities. You don't want your planet in this area. [Answer] Planet never sees smaller star. Your planet is at the L3 Lagrange point of the smaller star. Thus the big star is always interposed between the two. ![enter image description here](https://i.stack.imgur.com/Eh4xn.jpg) [Answer] We can clearly see the sharply-defined disk of our own sun, especially when it's filtered through a bit more atmosphere at sunrise and sunset. With a dimmer K-type star together with a M-type red dwarf, a habitable world would be closer and have an even better view. A thick layer of cloud cover would be a plausible way of obscuring the true nature of the stars. The fuzzy blob in the sky might often be redder on one side or change color if one star eclipses or transits the other, but the nature of the system won't necessarily be obvious to observers on the surface. Moons would only be visible as dimmer fuzzy blobs that occur at night, though. Another possibility is for the locals to have a very non-humanlike vision sense. Perhaps they can only clearly see short-wave light, though this would be odd considering the planet gets relatively little such light. Maybe they don't have clear vision at all, or are very nearsighted. Or their eyes just don't handle bright objects as well as ours. In any case, special viewing equipment would allow them to get a clear view. [Answer] Megastructure. Aliens have surrounded one of the stars with a Dyson sphere, Ringworld, etc. which consumes the visible light and emits infrared that you are not quite able to see, until science. Space oddity. Rather than a megastructure, electromagnetic life forms (distant descendants of the Common Sunspot) have taken up residence in the smaller star, and their ecosystem now releases only dim infrared light high in the coronasphere, after it has sustained the vast intellectual ferment of soaring prominences surrounding their Philosophers' Star. Protoplanetary disk. Both stars are surrounded by a vast ring of debris, and light filters through this ring. Tidal lock. To an approximation, your planet always shows one face to the two stars. (Because it is circumbinary, it can't just face one all the time) The part of the planet that directly faces the brighter star all the time is uninhabitable, as is the dark side; but in the habitable zone (of the planet, I mean) only the smaller star ever rises above the horizon. ]
[Question] [ The mule-dragons are a rare but extremely powerful type of dragon. They have a supernatural ability to seek out and hoard expensive shiny stuff like gold, silver, and precious stones, which they do near-instinctively. They will collect their riches through any available method, such as digging through rocks, or stealing from weaker beings. They also have human-level intelligence, can use language relatively well, and even have a small level of creativity and inventiveness However, despite their human level abilities, they are still very non-human and cannot speak human languages. This, obviously, would be a significant obstacle towards doing anything with their riches. There are also a small number of humans who are able to understand dragon languages The world they live in is, in terms of its societies and economies, the same as the real world today. These dragons, due to their low numbers and sparse spread, rarely encounter each-other and so cannot do much intraspecific trade Could these dragons realistically buy, sell, and generally participate in human economies? [Answer] > > They will collect their riches through any available method, such as digging through rocks, or stealing from weaker beings. > > > The mule-dragons will become rare and, if they were to participate to an economy, this would be done through the black market. People will not like to be considered "weaker being", give enough occasions of a stolen item surfaces, one which links to a mule-dragon thievery, and the fame of "mule dragons as thieves" (or even murderers) will start to emerge. Even more, some greedy (and rich) humans will invent such occasions, for the opportunity to plunder a mule-dragon cache. These humans have the means to influence the public opinion enough to organize hunting parties, especially if they promise a share of the hoard to the participants. The only way for the goods of a mule-dragon to seep into the economy would be through outlaws individuals - thus the black market. Keeping into account the low morals governing the relations with outlaws, the mule-dragons will need to very carefully manage the relation, good chances are they'll end dead anyway. [Answer] Given the power and accumulated wealth of the mule dragons, humans with the innate ability to understand them have an extraordinary employment opportunity as their interpreters. Given the power and appetites of the mule dragons, their interpreters have a strong motivation to not screw up in their duties. They therefore adopt the deference, manners and acumen of butlers or personal servants to their reptilian lords. Being even rarer than mule dragons, the good interpreters are highly valued by those dragons who are lucky enough to hire them. Therefore these humans developed some small measure of influence over their lords. At least enough influence to keep them from eating or roasting their business colleagues when deals fall through. The best interpreters bring style, clarity and a reputation for honorable dealings to their master household, enriching the profit potential for all involved. Other humans would be very foolish to try to deal with dragons who lack interpreters, especially if those humans possess or wish to acquire shiny things. But the presence of an interpreter assures propriety and safety on both sides, allowing these dragons to participate in the human economy with ease. [Answer] ## Obviously These dragonfolk have these qualities in common with humanfolk: 1. sophont intelligence & awareness 2. ability to communicate 3. ability to assign value to discrete sorts of materials 4. ability to reason 5. ability to act upon a desire with free will The only substantial difference you assign the dragonfolk is: 1. inability to speak human type languages You don't specify, but it is apparent that this is a physiological roadblock and not a cognitive one. Dragonfolk do have the language ability and speak a language; and there are humanfolk who can also speak it, so it can not be entirely alien (like a language spoken & received via radio waves). There are ways to work around physiological obstacles to understanding different kinds of people. Essentially, they will buy, sell and participate in the broader economy the same way any other minority group of people will participate, and that is much the same ways any two groups of people who don't speak the same language do. Since both humanfolk and dragonfolk are cognitively on the same level as regards economic activity, dragonfolk with sacks of gold and gems will naturally find the nearest pawn shop to unload their loot. Even without a common language, the two parties can make use of signs, pointing and shifting things in and out of the pile that's being considered for trade. As dragonfolk and humanfolk come into greater contact with each other, a trade jargon will eventually arise and this may evolve into a pidgin and perhaps eventually into an actual creole language. Such systems of communications could involve speech, body posture and signed symbols. It is also possible that written communications could be used between the two communities. [Answer] > > they [...] cannot speak human languages. Could these dragons realistically buy, sell, and generally participate in human economies? > > > The ability to understand each other's language is not necessary for commerce. You show me something I want. I show you something you want. If we can communicate "yes" and "no", we can trade. Humans have been figuring out how to engage in commerce without a shared language for (at least) centuries. Historically, you'll probably develop a [pidgin](https://en.wikipedia.org/wiki/Pidgin). By modern times, machine translation (or just communicating via computers) will greatly simplify things. See for example all the Americans that have bought something from China. ]
[Question] [ We have a human, magically protected so they can function in a vacuum. How will they be able to communicate? (The closest equivalent of suit radios--except they aren't wearing a suit.) I would think you could use bone conduction to replace a normal earphone (instead of moving a speaker cone the speaker moves something that's pressed against the person's head), but I haven't been able to think of any way of doing an outgoing message other than a keyboard or morse code or the like. [Answer] Some of the [mechanisms underwater divers use](https://en.wikipedia.org/wiki/Diver_communications) seem like they would work for this situation: * Hand signals / sign language / semaphores. This was used in David Drake's [RCN series](https://en.wikipedia.org/wiki/RCN_Series) extensively for crew that had to work outside the ship on the hull during FTL but could not use any electrical equipment since RF energy would send them off course. * [Divers' slates](https://en.wikipedia.org/wiki/Diver_communications#Slates) on which they can write short messages [Answer] [Lip-reading.](https://en.wikipedia.org/wiki/Lip_reading) Now this is something that people with hearing impairments and those working in noisy environments learn to do quite proficiently, and to a certain extent everyone does it from time to time. A camera on the lips/tongue would be able to transmit the images to a person who translates the images into speech. Alternatively, Google's [Deep Dream](https://www.newscientist.com/article/2113299-googles-deepmind-ai-can-lip-read-tv-shows-better-than-a-pro/) technology is professed to be better than humans at it. (That was back in 2016, New Scientist's report states. Even better by now if they kept improving it.] This can be converted to speech and or text as necessary. [Answer] Brain sensing headband. The person thinks about what he wants to communicate, headband picks it up, transmits it. Headband is calibrated to them, and forms the speech in their voice. Incoming communication is passed to them in the same way, with brain waves, or through bone conduction, behind the ear. Virtual keyboard, based on eye movement (like Stephen Hawking's). It could be built inside some special glasses, or a contact lens. Incoming communication could be through the same interface in written form, or again, through bone conduction, through the glasses, or a separate headband, etc. [Answer] AI supported communication. For example: my smartwatch actually shows me some decent answers when being asked something on whatsapp. Often times I can just use the prompts to answer. Now an advanced AI could communicate for you. You could have any kind of wearable that reads things like pulse etc. and could calculate proper responses for you which you can choose on that wearable. Going even a step further we could do something that might be even possible [soon](https://www.washingtonpost.com/technology/2021/02/04/chat-bots-reincarnation-dead/). An AI created from your personality which communicates for you completely. It can assess the situation through small cameras and knows exactly what you want to say. Alternatively you can wear glasses which read your eye-movement and have something like Dr. Hawkings had. [Answer] Sign language Hand signs and an old standby when noise or need for silence prevents verbal communication. full blown sign language should work just fine as well, without suits the full range of motion is available. I could even see what starts as just a hand full of signs getting slowly expanded into a full blown sign language. fire fighters, construction crews, soldiers, dive crews, air traffic control, and rescue crews already use hand signals. [![enter image description here](https://i.stack.imgur.com/UDfCd.png)](https://i.stack.imgur.com/UDfCd.png) [![![enter image description here](https://i.stack.imgur.com/9nyHp.jpg)](https://i.stack.imgur.com/9nyHp.jpg) ]
[Question] [ Let's say that you have a commercially/privately-operated jet aircraft. It's not something that's going to be used by a single pilot, or someone making mail runs, or a bush pilot; it's more of the type of thing that would be run by a commercial airline, or a UPS-style delivery company. You will see why. Now, unlike most jet aircraft, this one runs on a [nuclear jet engine](https://en.wikipedia.org/wiki/Nuclear-powered_aircraft); specifically, a fission model, and one of the [indirect air cycle](https://en.wikipedia.org/wiki/Aircraft_Nuclear_Propulsion#Indirect_Air_Cycle) variety, in which the reactor is not exposed to the inside of the engine but instead heats it via a series of fluid loops (likely liquid metal or sodium). Advantages to this include: * time aloft is no longer limited by fuel supply; instead, it is limited by crew endurance * an absence of greenhouse gas emissions * the reactor can be used to provide electricity for the rest of the aircraft * a vehicle with this type of propulsion can operate in zero-oxygen atmospheres, as it does not rely on a hydrocarbon-oxygen combustion reaction However, this model of aircraft is commercially owned and operated. That means that, instead of it being some kind of experimental vehicle piloted only by test pilots, there are going to be thousands of the things, and they're not going to be exclusively flying over test ranges anymore. Also, these things are pretty big - imagine, say, a [737](https://en.wikipedia.org/wiki/Boeing_737), with the absolute bare-minimum size being something like a [DC-3](https://en.wikipedia.org/wiki/Douglas_DC-3). Given that this aircraft runs on a fission engine, which is radioactive if breached, as well as that it runs on fuel that is probably quite valuable to any hijacker, what safety features or operational standards would it require in order to become commercially-viable? [Answer] ## The nuclear engine would have to be in a black box. Normally used to store flight recorders, the (not actually black) black box is very durable and extensively tested against hostile conditions. > > Now to the testing, which is insanely intensive: > > > > > 1. The black box gets shot out of an air cannon at 3,400 times the force of gravity (or 3,400 Gs, if you’re cool/still like to quote Top Gun). It hits an aluminum target at about the force of a jumbo jet hitting the earth. > > > > > 2. For five brutal minutes, it’s crushed with 5,000psi (pounds per square inch) of pressure to ensure it can withstand a sustained impact. > > > > > 3. To test it against fire, the box sits inside a 2,000 degree fireball for an hour. Without sunscreen. > > > > > 4. Then, testers do a full-on Jacques Cousteau and drop it into a pressurized saltwater tank, simulating the water pressure at 20,000ft below the surface. For 24 hours. In a slightly less-pressurized environment, it must then survive 30 days completely submerged in saltwater. > > > > > 5. And if all that wasn't enough, a 500lb weight with a quarter-inch pin sticking out is dropped on the box from 10ft up to make sure it won’t puncture. > > > > > If all that goes well, then the unit is run through a series of diagnostic tests to see if it still works. > > > The nuclear power engine would need similar testing, to ensure that the plane could fall out of the sky and crash and the nuclear material not leak. It should also be made very hard for someone to steal the waste. A safecracker could do it in time, but not quickly. The weight requirements would be significant, but the extra power should let you run more powerful engines, so it balances out. ## The waste design and flight path would need to be such that it was less vulnerable to terrorism. Some risk is understandable. Hospitals and industry people already use a lot of radioactive material and have crappy security, and we haven't had a dirty bomb made yet. That said, the flight pattern and waste disposal should be done to minimize the risk. They shouldn't fly over countries that might abduct them, and shouldn't land in countries that might have people attack them. They should make sure the waste is stored in ceramics or vitrified glass form, making it hard to weaponize it into a dirty bomb. [Answer] Special disaster-resistant fuel. [![triso fuel](https://i.stack.imgur.com/wYvly.gif)](https://i.stack.imgur.com/wYvly.gif) A fission reactor means you need fissile elements. It is possible to process these elements to minimize the chance of them escaping into air or water in case of a disaster, or even the chance of their participating in a runaway reaction. An example: triso fuel. > > Tristructural-isotropic (TRISO) fuel is a type of micro fuel particle. > It consists of a fuel kernel composed of UOX (sometimes UC or UCO) in > the center, coated with four layers of three isotropic materials > deposited through fluidized chemical vapor deposition (FCVD). The four > layers are a porous buffer layer made of carbon that absorbs fission > product recoils, followed by a dense inner layer of protective > pyrolytic carbon (PyC), followed by a ceramic layer of SiC to retain > fission products at elevated temperatures and to give the TRISO > particle more structural integrity, followed by a dense outer layer of > PyC. TRISO particles are then encapsulated into cylindrical or > spherical graphite pellets. TRISO fuel particles are designed not to > crack due to the stresses from processes (such as differential thermal > expansion or fission gas pressure) at temperatures up to 1600 °C, and > therefore can contain the fuel in the worst of accident scenarios in a > properly designed reactor. > > > These are in little fuel jawbreakers. Don't eat them! Well, one will probably be ok. In any case, the coating keeps the fuel under control. There is much riffing on this - QUADRISO fuel etc. A dirty bomb is still possible. They would need to crack and process the coated fuel to allow radioactive materials to disperse with the dirty bomb. That would take some doing. It also occurs to me that using an unusual but legitimate fuel like thorium or unenriched uranium metal could limit the usefulness to terrorists who want to capture these materials to make a nuclear bomb. Bomb plans are probably pretty specific as regards starting materials. [Answer] ## In addition to the other mentioned items You are going to need a lot of shielding. Fission reactions emit a lot of neutrons. Neutrons need a lot of shielding, but gamma radiation is an even worse problem. Figure on a 60 cm thick wall of lead to reduce gamma radiation by a factor of 1000. Given the intensity of radiation in the core, I would probably specify 100 cm of lead. This of course will be insanely heavy to fly around with. Throw away all high-pressure designs. The extra weight to have a flying containment vessel would be insane. Most of our commercial reactors are based on pressurized reactors, so you have to use a design for which there is limited experience. E.g., the molten-salt designs proposed for nuke-planes for the USAF. Note that limited design experiences means additional cost and delay in order to get a license to even fly a test plane, no matter if your genius engineers could get the design right the first time. Your reactor design has to be suitable for zero or negative gravity. Even though you don't plan on flying combat maneuvers or such-like, strong air-currents can result in negative gravity for a plane. It would be very nice if your plant is designed to cope with this condition instead of going super-critical during such an event. I know that some reactor designs would fail because they rely on gravity (e.g. coolant pools.) Materials exposed to radiation are damaged by it. Bombarding engineering materials with hard radiation causes both chemical and nuclear changes. All material in such areas will have to be designed to withstand the expected radiation exposure with tolerable degradation, and this almost means certainly means accelerated inspection and replacement schedules should be expected. Even more redundant safety features People like their redundant safety measures when nukes are located on the ground behind hardened bunkers. Before they let you fly, expect that the safety features required will be redoubled. Don't forget your whole-plane parachute People are going to be nervous about the nuke-planes. Hard to imagine that this won't be a licensing requirement once somebody decides it is a needed safety features. I am pretty sure I would lobby for it (after shorting your stock). Some serious liability bond is in order OK, say you are running your nuke-plane fleet and some terrorist takes one down with a missile. When you lose containment in the middle of the big city, you are going to face a huge class-action suit. Without such a bond, you are not going have investors or be licensed to operate. Not the safety equipment you were thinking of perhaps, but nonetheless essential. [Answer] Emergency stop A nuclear reactor in an aircraft should have the most important safety feature any nuclear power source has: emergency stop. In this case, that stop could occur at 40.000 Ft, in an aircraft with passengers, and little gliding capability because of its weight. At least three very large and strong parachutes would be needed, plus near water, to get the aircraft safely down. Without parachutes, to be able to land safely at any time, consider propulsion that can run on both nuclear energy and fuel (Cerosine), a hybrid engine construct was introduced by the Russians when they developed Tupolev Tu-119, which succeeded their early nuclear prototype Tu-95. Emergency Cooling A nuclear power source needs emergency cooling and a relevant amount of cooling fluid at hand. In a submarine, cool water is abundant, it just needs a safe inlet. But in an airplane, the cooling installation and its coolant would add considerable weight to the aircraft. Shielding Weight issue too. See the other answers. Military prototypes failed on it, ref [The Atlantic Jan'2019](https://www.theatlantic.com/technology/archive/2019/01/elderly-pilots-who-could-have-flown-nuclear-airplanes/580780/) [Answer] The big problem with powering an aircraft using a fission reactor is radiation. The substances used to stop the radiation from escaping: lead, water, or concrete, are all very heavy. Consider the case of the [NB36H](https://en.wikipedia.org/wiki/Convair_NB-36H), a US B-36 bomber modified to carry a small fission reactor. The reactor didn't actually power the aircraft, it was just a test to find out what happens when you put a reactor in an aircraft. GE did some early work on a jet engine that used the heat from the reactor to power the engine, instead of burning fuel. Problem there was it tended to irradiate particles in the air, leaving a radioactive trail. Bases that operated such an aircraft would have had a real problem with residual radiation. With the NB36H, the crew compartment was lined with 11 tons of lead, making it very heavy. And, while the NB36H did fly a number of times, and the shielding was found to be effective, the disaster that would result from a crash, including a runaway meltdown of the reactor core, put an end to this idea. The Soviets had an almost identical program, the [TU95LAL](https://en.wikipedia.org/wiki/Tupolev_Tu-95LAL), which was abandoned for the same reason: the radioactive trail it left in the air, and the dire consequences of a crash. Presumably a nuclear powered aircraft would use a similar shielding arrangement, but it would also face the dual problems of leaving a radioactive trail in the air, and the results of a crash. ]
[Question] [ We hit a point in warfare very very long ago where no creature was truly dangerous to a modern military. But could a creature that is be made? This creature has to be able to pose a serious dangerous in a confrontation with a modern military. Not just at terrorising civilians. It can be multiple different species working together, it doesn't have to just be one creature. It doesn't need to be dangerous in an open field. Being dangerous in swamps, dense forests, urban environments, etc. It just needs to work well enough in enough different environments to have a military feel it would be worth the money for it. It shouldn't die off as soon as humans stop providing it resources. It needs to be able to somehow provide threat to tanks & have a way to hide from airpower. It only needs to be theoretically possible to create but not like the blob where it makes zero sense at all. It should be some sort of realistically sized animal. That isnt a microbe. Would this be possible to do in a semi-realistic way? edit: i want something to live in nature is able to cause serious pain in the assery to developed nations. It doesn't need to be able to cause collapse, just be a threat [Answer] ## Pathogens Create a disease organism that meets your requirements. Exactly what counts as a creature is up to you, viruses and bacteria would not count, but whether [Giardia](https://en.wikipedia.org/wiki/Giardia_duodenalis), [Plasmodium](https://en.wikipedia.org/wiki/Malaria) or [Trematodes](https://en.wikipedia.org/wiki/Trematoda) count is a question. How to weaponise it will be a question. If you just need area denial then just being dangerous to anyone would work. You may want to make it a bit more "sci fi" by introducing nationality / racial specificity. Another option would be to require a specific (viral?) antidote, that is available to your troops but not the enemy. [Answer] ## Fairly recently, Australia declared war against an animal species. They lost. [Emus are resistant to gunfire. They are very fast. They're very smart. They are a serious threat even to a modern military.](https://en.wikipedia.org/wiki/Emu_War) > > In the days that followed, Meredith chose to move further south, where the birds were "reported to be fairly tame",[11] but there was only limited success in spite of his efforts.[2] By the fourth day of the campaign, army observers noted that "each pack seems to have its own leader now—a big black-plumed bird which stands fully six feet high and keeps watch while his mates carry out their work of destruction and warns them of our approach".[12] At one stage Meredith even went so far as to mount one of the guns on a truck, a move that proved to be ineffective, as the truck was unable to gain on the birds, and the ride was so rough that the gunner was unable to fire any shots.[2] By 8 November, six days after the first engagement, 2,500 rounds of ammunition had been fired.[6] The number of birds killed is uncertain: one account estimates that it was 50 birds,[6] but other accounts range from 200 to 500, the latter figure being provided by the settlers. Meredith's official report noted that his men had suffered no casualties.[2] > > > > > Summarising the culls, ornithologist Dominic Serventy commented: > > > > > The machine-gunners' dreams of point blank fire into serried masses of Emus were soon dissipated. The Emu command had evidently ordered guerrilla tactics, and its unwieldy army soon split up into innumerable small units that made use of the military equipment uneconomic. A crestfallen field force therefore withdrew from the combat area after about a month.[13] > > > > > If we had a military division with the bullet-carrying capacity of these birds it would face any army in the world ... They can face machine guns with the invulnerability of tanks. They are like Zulus whom even dum-dum bullets could not stop.[12] > > > As such, Emus or other similar birds would make a great model for a creature designed to destroy tanks. Genetically engineer them to be a bit tougher and more bullet resistant, a bit smarter and more able to used guerilla war tactics, a bit stronger, faster breeding, and most importantly, able to drink petrol, oil and other such fuels, along with a thirst for human blood. Then you release them into a rival country. They won't be able to stop tanks, but they will be able to stop trucks and fuel delivery. Using hit and run tactics and their great speed and intelligence they can destroy the fuel supplies of tanks and prevent tanks from being able to resupply, while picking off any humans who leave fortified compounds. They can eat enemy crops and food supplies and generally make it very hard to prosecute any sort of war. [Answer] Make it fast, really fast. Make it small, really small. Make there be many. Humans have never won a war against cockroaches, ants, bees, wasps or mosquitos. The cost of engagement is just too high and the only solutions are poisons/toxins. Here in NZ we are also fighting rats, mice and possum. They can't hurt us (though they do hurt our birds), but fielding the military against thrm probably wouldn't be effective Thus the solution is ..... the fetid rat. Infect rats with a disease and make them overly agressive (go out of their way to bite people), and make them just a touch smarter so out current traps don't work. --- Human military is aimed at human-speed, human-sized targets. We can also engage things slower/bigger, but our ability to engage multiple small fast targets is on the edge of our weapons capabilities. How fast can humans swing a gun? Or if the gun is automated, how fast can humans give it targets? Things are changing with CIWS. Systems that can engage incoming missiles have become a reality, but they are expensive to operate and probably can't engage multiple targets for extended durations. --- See also: Scary Robots: <https://qntm.org/robots> [Answer] Some form of aggressive and poisonous flying insects attracted by heat, think "super-mosquitoes". They fly in huge swarms and flock on humans, stinging them to death and maybe using their bodies as nests (the same way flies lay their eggs in food). As for tanks, they will swarm engine decks and clog the filters which will kill the engine over time. Have their blood/poison be acidic enough to attack steel and they will slowly but surely melt through to roof of a tank (top armor on tanks is usually pretty thin). Death by a million cuts. Larvae are able to burrow in the mud/sand/grass and lay there dormant until a prey is detected, at which point they will latch on and shortly after hatch and attack. Bonus answer: A super fast spreading fungus with corrosive properties. It could cover whole areas in spores and over time wear out vehicles and weapons. [Answer] I'll use traits from existing animals. While DNA is not a literal blueprint, it does define the shape, placement and effectiveness of the body and organs. Additionally symbiosis like Mitochondria already do and Chimerism (multiple DNA sets in one organism) could further improve the chances of successfully integrating other animal traits into one animal. When bulletresistant animals come to mind, the Elephant and Grizzlybear (and Badger) are high on the list. Elephants have thick skin and a lot of meat before vitals are hit. Grizzlybears and Badgers both have a thick, loose skin able to take an aweful lot of punishment. Going with Grizzly bears because they are ommivores that already hunt humans successfully from time to time (stealthily!) And have the ability of hibernation. You want to enhance their bullet resistance and spider silk is a great way to do that. By placing many spidersilk glands inside the skin layer amd migrating the strands throughout the skin layer you can give the skin an additional bullet resistance on par or superior to Kevlar. You can also enmesh the fur of the bear with spidersilks as additional protection. You naturally want your creature to be dangerous, so lets make its nails an incubationground for the botulus bacteria, which secretes botulinium. One of the, if not the, most dangerous toxins in the animal world. You do need some protections to prevent the toxin from killing the bear ofcourse. Similarly other, less lethal toxins can be used. For a given amount of "less lethal" when the only difference is less than micrograms for a lethal dose. For additional intelligence you replace the existing brain tissue with that of certain birds like Ara's and Crows, which have denser neurons allowing them their intelligence despite their small size. You may want to add a group of similarly modified Badgers to the mix. You can take away their fur and replace it with various octopus skins, like that of the catfish. That enables them to simulate immense amounts of camouflage patterns and even neon-like lighting if necessary. The ferociousness, small size and speed make them formidable animals. Badgers despite their size can already survive some handguns and even the powerful bites of lions. They would offer resistance (not immunity) to larger fire arms as well. [Answer] Other answers give some good ideas. But how about: think of sabotage instead of direct combat. If you can cause the enemy's equipment to malfunction commonly (or at least in battle) then you've given yourself an advantage. For this one of my first choices would be small rodents. Think along the lines of mice or chipmunks. They can get into all kinds of places. They can chew on electrical cables and maybe some fuel lines. They can build nests in places where airflow is needed (engine intakes, etc). There's probably more kinds of trouble, but those are good enough to start with. If they're genetically engineered to grow rapidly, breed frequently, and not fear common predators, then unleashing a swarm on your enemy is going to be problematic for them to control. As a bonus perhaps genetic engineering can work around some common poisons and such deterrents. Of course, this could be a double-edged sword. If they end up infesting your own side's equipment, then you've sabotaged yourself. So you would want to further genetically engineer some kind of special deterrent (pheromone, chemical, sound, etc. take your pick) that you keep as a top military secret and deploy to your own forces in a way the leaves as little chance of anyone figuring it out as possible. [Answer] Such a creature probably wouldn't look much like anything based on Earth biology. But given that it's genetically engineered, perhaps this can be contrived. It needs to be fast moving. Perhaps not as fast as a jet or even a humvee, but able to move at human sprinting speeds, let's call that 15mph+. It needs to be difficult to target, so smaller than the typical infantry soldier. Anything smaller than a cantaloupe should suffice. But perhaps even smaller is viable... something the size of a grasshopper isn't entirely ruled out, provided that it can offer some threat as you've outlined. To offer threats to infantry, this thing's just going to have a stinger with some vile form of venom For tanks, it's more difficult to think of how it could disable the tank (but let's face it, even when the crews are murdered, sometimes those are just hosed out and welded together again). So, the primary mode of attack will be to attack the crews, which are rather vulnerable even if it seems like they aren't. Tanks need air, they aren't self-contained atmospherically. If we have the insect-sized attackers, you'll want a swarm behavior to clog air intakes, both to stall out the motors and to choke out the crews until they attempt escape. But if you could have the melon-sized attacker, I also wonder why it couldn't be programmed to stuff itself down the barrel. It wouldn't be foreworthy until the obstruction was cleared, without that firing the gun risks blowing the thing. Such a tactic could put the thing out of commission for days. And if the organism were capable of excretions that could permanently foul the barrel... just wow. For instance, there are some deep-sea organisms that can secret metallic iron, depositing it in a way reminiscent of electroplating. I'm not sure how much would need to be deposited on the inside of an M1 barrel to make it permanently unfireable, but it's not some massive amount either, not a quarter-inch or anything like that. Such an organism would ideally be "protoplasmic" in its body composition, with no distinct organs that could be damaged (immune to small arms fire). Unable to fly, they might hide away in dense foliage, waiting for a tank to come through. Even up in trees, waiting to fall down on top when they sense tanks rumbling by underneath. The insect model is nice too, because with flight they could be quick and deadly. Swarming would be horrific, and large swarms might even be resistant to flamethrowers (in the "we can weather attrition more than you can" sense of the word). Your super-murder-hornets might, for instance, have some novel venom that is simply corrosive in addition to being ordinarily venomous... there won't be much antidote if it's eating away the flesh that it was injected to. Or maybe they just harbor the microbes that cause necrotizing fasciitis. Thus even if given the antidote, they will only recover from the venom and not the resulting infection. Their stingers aren't one-shots like honey bees, they can run around being vicious little shits. Long enough to penetrate most chemical warfare protective equipment, and all of the uniform save maybe the boot leather. ]
[Question] [ I have a small character in the book I'm writing who is a member of the Fae. We're talking old school folklore, Horned King, Oberon, changeling level Fae and not Peter Pan teeny tiny wings type. One of my main characters has been massively slighted by her and is going to put something in her drink to make her sick in front of lots of people. Not kill, just embarrass. Any ideas as to what I could use? [Answer] ## An iron tablet. Fae don't like the touch of cold, manufactured iron. What is more cold and manufactured than iron that comes in a pill, to help people with iron deficiencies and heavy periods? They could find out from books the dosage needed to make the fae feel raw and burnt inside, and not kill them. ## St John's Wort. Known to have protective properties against the fae, it's commonly used in herbal medicines and drinks, and so would make a great poison to add a bit of punch to the drink. [Answer] Get another Fae to make them sick. From what I remember of the Fae from Changelings, you're not about to make one sick with a mere human trick. Arcadia is far too capricious for that. However, another Fae may know a weakness to exploit. It may come in the form of an adulterant to a drink. This particular adulterant would be extremely specific to the individual Fae being targeted. That being said, there will most certainly be a price to pay. Whether your character understands the price before it's too late is entierly up to you. [Answer] Holy water can have an effect in some stories. Salt is also supposed to dispel fae magic Either of these could be used to poison a few. Perhaps in the case of salt it could be made to look like an accident. ]
[Question] [ If we assume a method of instantaneous teleportation, where an object such as a human or simply a sphere is instantaneously physically removed from one location and transported to another, what kind of a sound or physical effect (eg. shockwave) might this create on departure and arrival in an atmosphere? On departure, we can simply assume that the space occupied by the object is now a pocket of perfect vacuum surrounded by regular atmosphere. This seems like it would be relatively possible to solve using real physics. Arrival is more difficult. The air could either be physically pushed out of the space the object will be occupying, which seems like it could have catastrophic results if the air molecules reach relativistic speeds, or it could be teleported out of the space into eg. the immediately surrounding space. Not expecting hard real-world physics answers for this part. Bonus questions: * Would making the teleportation slightly-less-than-instant by adding a time delta of eg. 10 milliseconds for removing/pushing the air help avoid it being a lethal or cataclysmic event? What would be the smallest reasonable time delta? * How would the situation be different if performed in water instead of air? [Answer] ## Teleport how? There are a couple alternative mechanisms beyond what you suggest. One that I've seen used in fiction is that the teleport swaps whatever is in the target space with whatever was in the originating space. This kind of teleportation should be nearly silent (at both ends!); the only sound would be that generated by breaking molecular bonds in any solids that are divided by the boundary of the teleport volume. Another is to have whatever is at the destination interpenetrate with the teleported object/body. Strangely, doing this with air at atmospheric pressure might be (I've read) survivable, because of the relatively low density of air at standard conditions (dust particles could be a big issue, however, and stone or wood would be very, very bad). With air, at least, this should again be almost silent. The mechanism put forth in the novel Jumper (Stephen Gould, 1992 -- ignore the film, it didn't represent this the same way) was that the titular jumper actually opened a portal and simply slipped through; this took long enough that there was no actual sound (it was more like taking a quick step than what we usually think of as a teleport). ## Your Way If we choose only your mechanisms, all it takes is that the teleport not arrive all at once to avoid the relativistic air molecules -- if it takes even a millisecond to go from feet to head, you'll get a bang (essentially a sonic boom) similar to the one at the origin end (in fact, the origin bang will be reduced compared to instantaneous vacuum, because there's a progression instead of a discontinuity), as opposed to nuclear-explosion level disaster. If the energy to push the air out of the way comes directly from the body being emplaced, it'll be similar to a supersonic aircraft ejection without the protective capsule -- pressure applied over the entire body comparable to that of a concussion grenade, and likely fatal. If, on the other hand, the energy is supplied by the teleportation effect itself, it'll still be felt (the rebound of the pressure wave, at a minimum), but won't be like the explosion of a bomb, anyway. At the departure end, either way, you'd get a similar level of vacuum to what's created in the collapse of a lightning strike's plasma tube -- and of similar cross section (though vastly smaller length), so the sound would be roughly similar to a very nearby lightning strike (without the drawn-out effect you'd get if it were tens of meters away and you heard sound from the length of the bolt). ## Water? Now, to teleport into or from water complicates things due to the density of water compared to air (though it worked very well in Vernor Vinge's novel The Witling -- his was the source of swapping destination with source -- and was needed there to deal with momentum conservation). If you take even ten milliseconds to push a human-sized volume of water out of the way, the amount of energy required will approximate that of a hand grenade -- and do similar damage, by producing literally explosive levels of pressure. The inertia of the water would actually reduce the sharpness of the clap at the origin, however, but might also result in effects similar to micro-cavitation (which has been hypothesized to produce nanoscale hydrogen fusion). [Answer] It would sound a bit like (not exactly like) thunder. [Lightning](https://www.loc.gov/everyday-mysteries/meteorology-climatology/item/what-causes-the-sound-of-thunder/) causes expansion and compression in air, too. > > As lightning connects to the ground from the clouds, a second stroke of lightning will return from the ground to the clouds, following the same channel as the first strike. The heat from the electricity of this return stroke raises the temperature of the surrounding air to around 27,000 C° (48,632 F°). The rapid rise in temperature creates a rapid increase in the air pressure as well, rising to 10 to 100 times the normal atmospheric pressure. Under such pressure, the heated air explodes outward from the channel, compressing the surrounding air. As the heated air expands, the pressure drops, the air cools, and it contracts. The result is a shock wave, with a loud, booming burst of noise sent in every direction. > > > [Answer] [![enter image description here](https://i.stack.imgur.com/z0xns.png)](https://i.stack.imgur.com/z0xns.png) ## How is Important As others have already stated, how is very important. Let's imagine the case above, where your 3D "You Are Here" is encapsulated in a 4D bubble and lifted from one part of the 3D world sheet to another part of the same 3D world sheet. From the point-of-view of an observer outside of where you left, you completely vanish the instant you begin moving. However, gasses, liquid, energy, and other matter, can probably flow freely in all 4 dimensions. So, hopefully whoever created this bubble packed extra, or you'd lose pressure momentarily. Let's assume that for now. The region your leaving has no pressure drop. The area of overlap between the 4D hypersphere and 3D space is only $\pi R cos \theta$, which will drop the zero when the hypersphere is no longer touching the departure part of the world sheet. However, at no time will the pressure change. So, at the point of departure, there would be no sound. At the point of arrival, things are a little different. There are not one, but two atmospheres worth of gasses in the arrival part of the 3D world sheet. This will not really create a sound, just a gentle rushing of the wind, unless the hypersphere slams into the arrival 3D world sheet at a good fraction of the speed of sound. When "You are here" arrives, it will appear instantaneous. But it was preceded for a short amount of time by the atmospheric gasses that had more degrees of freedom inside the 4D hypersphere. [Answer] Depends on the teleportation mechanism. departure if instantaneous, then you'll have a thunderclap. Imagine the sound of a paper bag being exploded, magnified about 50-100 times. arrival if instantaneous, then the same, plus the yowl of the poor soul being transported, which will feel a tremendous backlash. Superficial cellular damage a very strong possibility ("transportation sunburn"), hydrostatic damage possible, damage to eyes and especially eardrums almost certain. To avoid these pitfalls transporters are usually imagined as either exactly swapping the same volume at the two ends (this is how renging works in Vinge's The Witling), thereby eliminating also the departure boom, or "projecting" some kind of displacement field, that creates a vacuum just before the teleportation happens (this limits the ear-busting problem to pressure differential between the two points, which is limited to a maximum of 780 millibars and that if transferring between the Everest mountaintop and sea level (of course, entering a hyperbaric chamber isn't recommended in either case). ]
[Question] [ My world consists of a large number of islands laid out in a hexagonal pattern, each one circular and large enough to support a small community. At the center of each island an obelisk sticks out of the ground, ancient and seemingly indestructible. In between the islands is a sea made of a liquid called kesh. From the island dwellers perspective, there are three main properties of kesh. First, it slowly but fully corrodes anything it touches down to component molecules, and complex molecules into simpler ones. Second, it is of a fixed quantity - you can't make kesh into anything else, but neither is anyone able to make more if it. Third, it's very heavy. Just about anything floats in it, and if it doesn't at first it will when it's been broken down. The reason the islands are still there is that the obelisks repel kesh from them, up to a certain distance. Legends say that ancient people made the obelisks to fully protect their land back when it was a whole continent, and their power and protection radius has dwindled over time - but no one knows for sure. Anything that falls of the islands eventually dissolves, turns into dust that floats on top, and is moved by waves or wind until it drops down on an island again so all matter eventually circultes. You can move between islands by flying, or by boat if you don't mind constant hull replacements. Water runoff make thin layers on the kesh that tend to quickly evaporate again. Kesh remains liquid at all temperatures. This is all information that the Islanders know. Now, here's my problem: I want these islands to all be fixed in position, same as any island in the real world. But by this logic, the kesh would eat away at the foundations and bedrock until all the obelisks were independent, and they would start floating around freely with air bubbles around them. How can I set things up so that the islands would remain fixed, without changing anything from the islander perspective? Bonus points for explaining how the bottom of the sea works. I would prefer for there to be bedrock down there and not magma, but it's not necessary since no one will go there. I will also mention that there is magic in the setting, though it's a fully separate system from however the kesh and the obelisks work and can only be used by living things. This means I'm not averse to fantastic solutions as long as everything is consistent, but it should be no more complicated than is needed. [Answer] # Cylinders, not Spheres There is no explanation for why the obelisks repel the kesh, so its mechanism is up to you - so rather than a simple radius, the obelisks repel kesh in a circle that is of fixed radius but unlimited vertical extent. (Or effectively unlimited.) So as to prevent the kesh from dissolving its way down to the core of the planet, why not have some magic energy generated by the core of the planet itself that the obelisks channel? So the kesh cannot penetrate beyond a radius of X km from the core, and the obelisks channel that same energy in vast cylinders of power that taper off somewhere outside the atmosphere? [Answer] Kesh is a runaway grey swarm and the obelisks have a counteracting grey swarm. The kesh is a biological, magical, or technological grey swarm, that eats everything it touches. The obelisks are a corrupted version of it, that emits its own swarm that feeds off the kesh within a certain distance. The kesh can't eat the foundations because the obelisks eat it. The bottom of the ocean is too high pressure for the kesh to function. Whatever makes it work doesn't work under high pressures. If you go deep enough it fails to work, so it doesn't eat through the planet. [Answer] Gold The obelisks are made of gold, which is very non-reactive. Furthermore, it is as simple as it gets -- it's elemental. You can't break down molecules that don't exist. Were they of silver or iron or copper, or most other metals, there might be a problem with the surface tarnishing/rusting/acquiring verdigris and the kesh breaking that down in a manner that erodes the metal. But not gold [Answer] Foundations already reacted with kesh Let's put aside answers that the bedrock or things like sand are probably not reacting to kesh. There is a very simple reason you've already given in your opening statement. Stuff reacts to kesh and is reduced by it to a dust. This dust doesn't react with kesh anymore, or if it is, can't be reduced further. Sure it'll float on top of the ocean at first, but what happens later is more interesting. The dust settles on a beach or is brought together in the ocean. With enough pressure it can start compacting. On the ocean it can get enough weight to start sinking, getting to greater depths with more compacted dust where it'll compact to bigger sizes thanks to the pressure depth. On land it'll just start geological processes that over the years creates more heavily compacted dust and rocks. Both ways can create the core of the planet. So you could even have basically added the kesh ocean to any planet, watch it dissolve into the crust and disappear. Over time the ocean will be pushed back to the surface as heavier things are created by all the processes, leaving a sturdy bedrock and even islands. When the obelisks are placed, they can stand on solid already reacted with kesh rock. The whole oceans are likely still full of dust and compacted dust not big enough to sink yet, so the obelisks allow for easy placement of the kesh sediment. This can then start changing to things that can be reduced by kesh again. ]
[Question] [ The setting is extremely cold all the time, and traveling around takes days. How would travelers bring water rations with them and keep it from freezing? There are almost no un-frozen bodies of water readily available, and I'm not sure if its realistic to have them melt down snow at camp each night. Or how they would use the water they boiled the next day, without making camp and boiling more water multiple times a day. [Answer] > > I'm not sure if its realistic to have them melt down snow at camp each night > > > You should consider that if they cannot light a fire when they camp at night then there's a reasonable chance that they might not live until the morning. Arctic nights are cold, and medieval insulation was either poor, or quite heavy. People who lived in the arctic would of course be suitably equipped and well practised in this sort of survival, and show that it is possible, but this isn't a skill that can be easily communicated to just any traveller at short notice. Inuit hunters would have consumed some of their prey raw, on the spot, including the blood... with mammalian prey, this is an effective way to stay warm as well as nourished and hydrated. They only cooked food when they'd been on the move for a day, but note that this implies that they carried suitable equipment to actually cook things (such as blubber-fuelled lamps). > > How would travelers bring water rations with them and keep it from freezing? > > > Note that it is possible to eat frozen meat, and the peoples of the arctic circle do just that. Not only will this help the meat to last longer, but if it was uncooked before freezing then it can contain additional nutrients not present in aged or cooked meat that are otherwise hard to come by in arctic winters, such as carbohydrates from intramuscular glycogen. Clearly it would be possible to keep some food and drink within the warm layers of the travellers clothing, though this would be a limited amount. If pack animals were available, such as caribou/reindeer, it could be possible to make use of their body heat to keep a larger amount of food and water thawed, though obviously that needs to be counterbalanced by the calorific and water demands of those animals. [Answer] I would say the best way to keep water from freezing is to keep it close to the body of the bearer. Flasks were usually made with the stomachs of lambs or other animals, so they were quite flexible. They could be stored inside the clothing, so to be both better insulated from the outside and also closer to the only readily available heat source. Replenishing them would require melting ice or snow whenever a fire is lit, but I guess the Arctic doesn't lack them. ]
[Question] [ If I take a [Rod from God](https://en.wikipedia.org/wiki/Kinetic_bombardment), drop it on to an ocean somewhere, what exactly happens? Let's say there's a secret base about 10,000 feet or so underwater. Is it still okay? [Answer] Lets use the Newtonian impact approximation... penetration depth is approximately $l\frac{\rho\_p}{\rho\_t}$ where $l$ is the length of the penetrator, $\rho\_p$ is the density of the penetrator and $\rho\_t$ is the density of the target. 20ft of tungsten hitting sea water at terminal velocity might be expected to go in about 114m or 374ft. This might not be a great approximation of penetration depth, but probably isn't out by an order of magnitude. Exactly what that would look like I'm not sure... a big splash, naturally, but most of the energy would be spent in the upper layers of the water. I'm not sure if the rod would be disrupted by the end of that 114m... probably not, so it might actually sink down far enough to go "donk" on the roof of the underwater base in an hour or so, but terminal velocity in sea water isn't quite as dangerous as in air. The amount of energy in a RfG isn't that great... only equivalent to a few tonnes of TNT, so I wouldn't hope for the initial impact to generate a shockwave capable of rattling your underwater base either. Using an RfG on anything on an abyssal plain is clearly a non-starter. But why use such an inappropriate weapon? Just use nuclear depth charges. Simpler, cheaper, more destructive. Don't overcomplicate things! ]
[Question] [ A hydra is a multi-headed beast usually depicted as a serpent in many mythologies. I suppose each head should have an independent brain and thus would each have a different wake/sleep cycle not unlike a dolphin (though the latter sleep with one hemisphere at a time to watch out for threats in the treacherous sea). With that out of the way my question is how hydrae chase down bird flocks for food? Dolphins achieve this by teamwork, but hydrae are independent, so how do they hunt down bird flocks since endurance isn't their strength in the air and neither is running on rough surfaces? N.B.: These hydrae weigh 100kg, are highly territorial and can fly at speeds of up to 65km/h. [Answer] They dive from great heights Your hydra spends all day flapping, flapping.... flapping. It gets high in the air. Then it soars for hours, heads blowing flaccidly about. When it sees a flock far beneath it, it dives like a squidly peregrine falcon. Each head is on its own as it traverses the flock, grabbing a bird each. The hydra is invulnerable of course and so makes no effort to slow down, hitting the ground at tremendous speed with a characteristic sound. [Answer] ### With tools All that extra brain power should go towards developing tools to hunt. I'd expect a hydra to hunt using a bow an arrow - otherwise what have those heads been doing all these years? They can harvest fibres from plants, spin them into thread, weave the thread into nets, and use those nets to hunt multiple birds at once. Stretch a net between two trees, scatter some food scraps on one side of the net. Flock of birds lands to peck at the food. Hydra jumps out, scaring the entire flock into the net. [Answer] ## Wing buffeting air disruption: Your hydra either sneaks or dives on the unsuspecting birds, then uses it's considerable size and wings to create sudden gusts of air that disrupt the flight of smaller flying creatures. This is most likely on the ground (knocking the birds over and preventing them from taking off to escape) but could, in theory, create so much turbulence as to disrupt the flight of birds mid-air. Tumbling birds desperately trying to take off or recover control are easy pickings for the multi-headed hydra that can come at an individual bird from multiple directions, essentially pack hunting without the pack. [Answer] ### They pull the old Scylla maneuver A hydra would be a terrible flying animal. They would by definition be front-heavy because of all their extra necks and heads (not to mention the large heart and lungs required to sustain said necks and heads), which would result in the animal being tipped forward while in flight and prone to be sent into a tailspin. Their body plans makes them not aerodynamic at all because the thickest area of the body is at their front, rather than the animal being in a torpedo or bird-like shape. On top of that all of the additional heads would be a liability when catching prey. The heads and necks moving every which way chasing prey would send the animal frequently off balance while in flight. At minimum it would require an extremely high degree of coordination, which would require huge brains with large flocculi per head, which becomes multiplicatively expensive for a hydra and kind of defeats the purpose of a hydra in the first place. What flight would allow a hydra to do, on the other hand, is get the hydra into position where it can attack unsuspecting prey. Sort of like what Scylla did in The Odyssey. Fly up to a high rocky crag where you know flying prey like birds or bats or small dragons are passing by and use your head to snag some of them as they fly past. This is analogous to how long-necked predators in Earth's past, such as Tanystropheus and plesiosaurs, are thought to have caught prey. Being able to fly increases the number of positions an animal can take to ambush prey, especially ambushing from above. A hydra may be a terrible flyer from a comparative perspective, but it still should be able to at least get itself into the air and haul itself over to a good hunting perch. A hydra would also have to have a high degree of correlation between its heads, and the heads would almost have to be linked somehow and not be fully separate organisms. The reasons for this can be seen in developmentally abnormal snakes that have two heads: when presented with food the two heads will fight with each other over who gets to eat despite the fact that the two have the same stomach, wasting time and energy. A fully coordinated hydra would be well-suited to using its heads to out-maneuver and corner small flying prey like bats and birds. As a corollary, getting up high and then snagging birds and bats as they fly past in large numbers is exactly how [snakes](https://www.youtube.com/watch?v=UbqVF2qaAcE) and [centipedes](https://www.youtube.com/watch?v=UROVfmY3NTA) hunt flying animals in real life, though none of them have multiple heads. ]
[Question] [ Let's ignore extraterrestrial visitors on Earth because I don't want to discuss twin paradox, we should be focusing on life inhabiting on another planet instead. Here on Earth we can do carbon dating because of plant and animal eat them even indirectly, it contains trace of C14, radioactive isotope produced as byproduct from the bombardment of cosmic ray, underground nuclear testing, etc. The alien sample should be exchanging C14 unless it dies and we know how to apply the known half-life of C14 to calculate their current approximate biological age, but does it hold true to other life in the universe as well? [Answer] First, a note - radiocarbon is useful for determining age as it is meant in an archaeological sense, the time since a plant or animal died. (And often was made into some human artifact.) It is not useful in determining age in the conversational sense of "the time since you were born". The basic principle of radiocarbon dating will work on (some?) aliens, but with caveats. First, it relies on the aliens' biosphere being carbon-based: in order to take up carbon-14 from the atmosphere, they need to use it in their tissue structure. All life on Earth is carbon-based, and there are some good chemical and physical reasons to suggest that it might be favorable in general, but non-carbon-based life is a longstanding trope in sci-fi, and they probably can't be carbon-dated. (There might be an analogue based on the properties of radioactive silicon or some such; I don't know enough about the chemistry of that situation.) Second, the dating part of radiocarbon dating relies on a number of assumptions and references that are valid on Earth. The amount of total carbon-14 in the atmosphere varies on a geological timescale. Different types of plant life contain different amounts of carbon-14, and therefore so do different animals, depending on their diet. Traveling to an alien planet, you would be essentially starting over all of this reference work. Through comparison with other methods of dating you could compile reference materials for a new world, but it wouldn't be as simple as dropping the sample in your Analyze-o-Tron and knocking off for a cup of tea. [Answer] Depends on how old you are talking about. On earth, many organisms continuously deposit hard tissue of some kind, and the rate at which tissue is deposited varies annually based on the waxing and waning of seasons. Namely, in the winter/dry season (for the tropics), growth is slowed because of a scarcity of resources, whereas in the summer/wet season, growth is faster. This creates a series of annuli (i.e., "rings") in the hard tissues of many organisms, including the rings of trees, [the number of lines of arrested growth in the cross-sections of long bones in most vertebrates](https://en.wikipedia.org/wiki/Age_determination_in_dinosaurs#Growth_lines), [the shells of mollusks](https://sciencenordic.com/ageing-denmark-geochemistry/new-record-worlds-oldest-animal-is-507-years-old/1392743), [the cementum of the teeth of many mammals](https://deerage.com/#:%7E:text=What%20is%20Cementum%20Annuli%20aging,winter%20on%20most%20all%20mammals.), and the [otoliths of fishes](https://myfwc.com/research/saltwater/fish/age-growth-lab/ageing-fish-otoliths/). Similar annuli form in the [earwax of whales](https://ocean.si.edu/ocean-life/marine-mammals/whale-earwax-what-you-can-learn-strange-collections) and [the eye lenses of many vertebrates](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5991300/), which aren't hard tissues but grow in a similar way. [There's been a lot of press recently about Greenland sharks living in excess of 100 years](https://www.researchgate.net/publication/306059132_Eye_lens_radiocarbon_reveals_centuries_of_longevity_in_the_Greenland_shark_Somniosus_microcephalus#:%7E:text=Radiocarbon%20dating%20of%20eye%20lens,marker%20of%20the%20early%201960s.&text=Radiocarbon%20chronologies%20of%20the%20North%20Atlantic%20Ocean.), but the way that scientists figured that out was due to a chance occurrence. Namely, the fact that the eye lenses of Greenland sharks lacked an enrichment of radioactive isotopes after a certain point that was created by manmade nuclear testing in the 1960s, called the "bomb pulse". The researchers then backcalculated the age of the shark based on the amount of growth predating the bomb pulse to the growth after, which they could do because they knew how much had occurred since the bomb pulse. This wouldn't work for most organisms due to the way radioactive decay works, the lifespan of most organisms is so short that the change in C14 enrichment ratios from two decades ago to now is barely even noticeable. Additionally, organisms are constantly taking in radioactive carbon isotopes through their diet, which is how it is possible to infer that an organism died so many years ago, death starts the radioisotopic clock ticking down because no new radioactive carbon is being incorporated into the organism. What's going to work best for your aliens is going to be entirely dependent on your alien's physiology. What researchers would look for is a long-lasting, slow-growing tissue, one that is sequentially deposited and rarely if ever remodeled. For example, long bone growth rings and sometimes tree rings can be secondarily obliterated, making it difficult to back-calculate the age. Assuming a generally vertebrate-like body plan probably the first thing people would look for is the eye lens, which is pretty consistent in estimating age across Earth vertebrates. [It may also work in cephalopods](https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0108935), but I don't think it would work in arthropod-like organisms because the eye lenses are shed and regrown with each molt. [In fact, there really isn't any good way to estimate the age of lobsters and other long-lived arthropods for the exact reason that no hard tissue is retained between molts](https://www.smithsonianmag.com/science-nature/dont-listen-to-the-buzz-lobsters-arent-actually-immortal-88450872/) . ]
[Question] [ This is a follow-up to [Government Maintaining Good PR despite zombies](https://worldbuilding.stackexchange.com/questions/195246/government-maintaining-good-pr-despite-zombies) and is another XCOM-inspired question. In XCOM, a substance called Meld ( a mixture of hybrid nanomachines, part nanobot, part microorganism) allows scientists to A) genetically modify humans and B) integrate nanomachines in human bodies to create cyborgs. My question is how the government would maintain good PR despite their controversial actions to prevent revolts/insurrections if a similar scenario occurred. Now, what is this "similar scenario?" There are three parts: 1. The elite among the aliens seem to have advanced psionic abilities (telekinesis, telepathy, energy projection, even mind control) and through a combination of gene therapy and reverse-engineered alien tech, select military operatives have gained the same abilities. 2. The government, using reverse-engineered alien tech and recovered alien corpses, have genetically modified select soldiers to have alien traits, including but not limited to: superstrength, superspeed, enhanced healing factor (think axolotl), chitin armor, flight, camouflage (which is advanced to practical invincibility), extreme resilience and/or durability (think cockroach or indomitable ironclad beetle, they're good examples of resilience and durability, as are rats...NOT speaking from personal experience, just an animal buff...) 3. The government, using advanced alien biotech, have created cyborgs-think humanoid, giant Battlebots combined with big, buff soldiers and you have the basic idea. Basically the 'mechs' so common to science-fiction, but integrated instead of separate (cyborg instead of human pilot/robot mech combo). No cyborg is more than 9 feet tall. In the first question, it turns out when there's a crisis or ongoing war, politicians are untouchable, but in this case, the aliens have been beaten and life is getting back to normal again. Except.....y'know, the government really didn't see a reason to inform military personnel's families of their extensive modifications during the war, they let military personnel contact their loved ones but made sure the secret didn't get out. Why? Because using poorly understood alien technology and genes to create super-soldiers is controversial, if not outright wrong, even if done with consent. It is obviously a poorly thought out plan, that only someone truly desperate would undergo, and yet this has happened. There will be an absolutely massive backlash (at least, if my reasoning is correct). Below are four different examples, each happening to a different person: 1. Your husband is called into action and you haven't seen him for about a year when he comes back, looking like a Goliath from Evolve. 2. Your military boyfriend comes back, clad in modern-looking power armor, and you're happy to see him; and then he tells you it's not power armor, that he was infused with nanobots and is now literally walking, talking half-alien tech....a cyborg. 3. Your brother comes back, his hair and skin now an eerie white, and he acts strangely. You wonder what happened to him, and finally he reveals that he's looked at the world differently after seeing it through the eyes of the aliens and zombies he's mind-controlled. You don't believe him, but then he lifts your pickup with his mind and shoots a lightning bolt from his hand that nearly hits you as evidence. "Now do you believe me?" 4. Your sister comes back, but she's acting so strangely that you consider having her tested for insanity. Finally, she tells you that she was turned into a zombie by an alien soldier and that while her humanity was partially restored by modern medicine (ie. she can think and act like a human,), deep down, she's still a zombie. Oh, and she's traumatized by her memories of being first zombified and then being mind-controlled to fight the aliens. My question is, How can the American government best handle this to A) keep their positive PR and B) dial down the backlash? *Specifically, the government has* to*: 1. Ensure benefits for those who agreed to modification and fought against the aliens 2. Prevent discrimination against those specified in 1 3. As specified in the preceding question, the mind-control ability of certain operatives is already set so they can't* use it on people; however, they can use it on aliens and zombies, and something tells me that will cause tension... .A) there will be that one guy who wants to bring his alien "pet" back home with him, B) there will be people mind-controlling select aliens to help the government uncover their secrets and recreate their technology and C) zombies will likely be protesting against the actions taken against them (ie. mind-controlling them and putting them on the battlefield) and calling for government action to ensure that they are not controlled again if they're not actively seeking revenge.... The government has to somehow account for all of that. Yeah, it's an awful lot to take in, I'd go step-by-step. As always, I appreciate your input and feedback, thanks in advance! As a final note, if this question needs narrowing down or fixing please let me know, and if you decide to close-vote or downvote, please don't do so without an explanation so I can keep improving my questions. [Answer] # A cover-up It would not play out like some kind of superheroes show on cable: "I have a terrible secret that's also really cool; I hope you don't force me to confess how awesome I truly am and then date the crap out of me!" That's harlequin romance trash. If military personnel are so irreversibly changed during the war effort, the government would prevent them from returning to civilian life, period. Families would be told that their loved-ones were killed in the line of duty, and there would be funerals with military honors. That would be the end of the public story. We know this is how it would play out because this is how clandestine services handle things in the real world. It doesn't matter how cool your dead dad's spy work was: they lie about it from the day he signs up to the day they bury an empty coffin. "He sold airplane parts for 30 years, and was killed when a gas main exploded. There are no remains." --- What truly happens to the combatants depends on what state they are in when the war ends. If they're able to continue functioning more-or-less like humans, they'd be kept alive in some kind of secret facility, effectively prisoners but with friendly jailers. They would remain in secret captivity until death. I don't mean cells: think permanent military installation during peacetime. They'll be free to move about within the facility. They'll be given jobs, if for no other reason than the therapeutic value of normalcy. At first, their "jobs" will be getting debriefed repeatedly, and while it will taper off after a while, it won't stop until the military is certain it has learned everything there is to learn about the war it just won. Later, they'd probably be tasked with analyzing intelligence. There would also be experiments; not gruesome or painful ones, but the military would continuously and actively study their health and abilities. They'll eat in the same cafeteria as the research and security staff. They'll have books and TV (censored) and movies, all the entertainments that can be enjoyed in secret. Perhaps the military would even keep tabs on their families for them, subject to psychologist approval. But they would never leave, never be permitted to have any contact with the outside world, ever. No phone, no mail, no internet. Any who try to escape or otherwise expose the project will be stopped, even if that requires killing them. If they succeed in contacting anyone on the outside, the government would sweep up those people, too. It's not hard to understand why they'd be kept alive. For one thing, each of these human weapons is a massive investment that has already been made. The military would not discard them if it could avoid doing so. It would keep them around for the next conflict -- whether that conflict is with more aliens or just some puny mortal dictator. And secondly, each of these human weapons is an experiment -- one that is still ongoing after the war. How long can a human survive after modification? What are the long-term consequences? Exactly what powers do they have and precisely what are their parameters? Could we improve on the process with the second generation? Given the amalgam of dissimilar technologies you've thrown into these things, we have every reason to assume there are unpleasant side-effects. Some will undoubtedly die from the long-term effects of their modifications. Some will require surgery to prevent death. The military will want to monitor these things as long as possible so that the next generation of super-soldiers will be better. The first generation isn't going to go off without a hitch; nothing ever does. There will be problems, and the military will want to study those problems for obvious and practical reasons. If nothing else, they would want to figure out how to make these modifications undetectable so that future soldiers might be able to return to civilian life. That would take decades of research. On the other hand, if any of the super-weapons is now so mentally changed that they are a danger to themselves or others during their lifelong confinement, they'd be euthanized. These are war heroes, so the military won't be cruel -- nobody will be vivisected alive. But anyone who poses a physical danger to the health or secrecy of the project will be put down as a practical necessity. Finally, it's worth considering that these individuals have just gone through a war, probably a uniquely horrifying one, and so even if their physical humanity could be magically restored, many will likely suffer from severe PTSD requiring ongoing psychological treatment. Because of the classified nature of their experiences, they'd only be allowed to talk to military psychologists who are part of the project and sworn to secrecy. And we may not be able to medicate them, given how physically changed they are. --- So, what would happen? They'll all be declared KIA. The ones who return from combat will be debriefed in secret and then evaluated with an eye toward viability as a long-term research subject. Those who are deemed not viable will be euthanized in a humane and extremely crafty way. The others will spend the rest of their lives in an underground research facility until and unless they're needed in another conflict, or until their situation deteriorates to the point that they must also be euthanized. As a result, most of the specific concerns you raise would never arise in the first place. [Answer] ### Serious option: Kill them off before they can retire. Depends on how far down the authoritarian slope the government has slipped, but it's easier to arrange a few thousand a military funerals, widow pensions, and a nice memorial, than to explain all that. If there's oversight and war reporters and helmet cameras and no press censorship - this isn't going to happen. But I'm including it for completion. ### Point to signed consent forms. This is what will happen to those who were modified by the surgeons. Hands will be washed of the issue because they consent to it. That it was allowed will be an issue, which will be dealt with: ### Scapegoating The general who decided to modify humans, and perhaps the general who lost the battle which resulted in the largest zombie hoard, will be expected to fall on their sword. They will submit their resignation and the government will try to wipe their hands of the issue. It wont work entirely, there will still be angry people out there, which will be deflected by... ### Hold a multi-year enquiry Politicians do this ALL THE TIME, "let's not get mad now, lets empower some researchers to interview everyone and gather all the facts so we can make an informed decision later." By the time the 500-page report arrives, a new government is in command, anger has died down, etc. These enquiries don't do much: * Australia's current bushfire royal commission is [forbidden from considering climate change as a factor in the devastating 2020 bushfires](https://www.theguardian.com/australia-news/2020/feb/20/bushfire-royal-commission-to-look-at-mitigation-but-not-climate-change), despite the hottest 10 years on record being, in order: 2016, 2020, 2019, 2015, 2017, 2018, 2014, 2010, 2013 and 2005. * In the 1980's, several Australian Aboriginal people who had been arrested were found dead in police cells [under suspicious circumstances](https://en.wikipedia.org/wiki/Royal_Commission_into_Aboriginal_Deaths_in_Custody), this spawned basically an Australian version of Black Lives Matter, which was deflected with a royal commision. [432 Aboriginal people have been killed in police custody since](https://theconversation.com/despite-432-indigenous-deaths-in-custody-since-1991-no-one-has-ever-been-convicted-racist-silence-and-complicity-are-to-blame-139873#:%7E:text=Since%201991%2C%20some%20432%20Indigenous,only%20ended%20up%20referring%20five.), and they remain, per capita, [the most incarcerated persons on the planet](https://theconversation.com/factcheck-qanda-are-indigenous-australians-the-most-incarcerated-people-on-earth-78528). While you're waiting on the conveniently delayed report... ### Give everyone medals, veterans discounts, call them heroes, and then ignore them. Quoting Justin's comment, as I can't add anything to it: > > Based on the track record of the American government in returning Vietnam vets, they would get everyone to say 'Thank you for your service', give them all medals, make them heroes, and then wipe their hands of any further involvement or responsibility. What is the difference between them coming back the way you describe and coming back in a wheel chair, or with PTSD, or with limbs missing? A broken body is a broken body. No need for any different response than the current one. > > > [Answer] Enclaves. It is hard to have sex with a 9 foot tall supersoldier. Unless, of course, you are also a 9 foot tall super soldier in which case what you need are durable surroundings. Weird looking mind reading psionic people are beautiful to other weird looking mind reading psionic people, and of course they both know it when they encounter each other. Your various engineered people will live in enclaves of their own kind where their idiosyncracies are the norm. There may be more to the alien engineerings than just battle prowess, and these folks will figure it out and grow into their new selves. These are not District 9 type internment camps and the persons are not blocked from interaction from the wider human populace. These are enclaves like Chinatown, the "gayborhood" or any other enclave of persons with similar ethnic, religious, or sexual orientation affinities who choose to live together in a given neighborhood. Persons based in these safe environments find strength there to pursue common interests, deal with the larger human populations and in this case, learn about their own new biology that circumstance has brought them. ]
[Question] [ An index is a measure of how a stock market is performing. Even the monsters know how to build up their portfolio. When a kill is secured -- say a human being -- or a carcass is recovered, they are cut up into many pieces and have their blood completely drained, then these parts will be distributed among the shareholders...so far still with me? So basically, they will trade these mutilated pieces among themselves, and occasionally, they will also offer performance shares, meaning free of charge, no obligation like a boss! They would even accept bones in exchange for meats etc., so that the weaker ones will have to dig the grave if need be. Now that humans clearly have the upper hand, using their cunning tactics and innovation to design better weaponry and traps to protect themselves against the monsters -- how can the monster index still growing strong? [Answer] Scarcity driven market. If the demand stays the same, but the availability of the traded good diminishes, the price of the good will go up, and so will the margins for those who manage to secure a delivery. It happens with shoes, clothes, cars, phones, immaterial services, whatever can have a price attached to it. Why would the MIT (Monster Indexed Trading) be any different? [Answer] A breeding program. Some monster is going to figure out where new humans come from and have an idea, "what if I keep some and make more?". That way you can bypass the hunting part, and most humans will gladly try to create their own food. You could perhaps give them a religion to keep them docile. Teach the children that monsters are higher beings that will eventually take the body apart and bring the soul to their God and they would even go (somewhat) willingly to their own slaughter. [Answer] Human cunning tactics The monster index is being driven up by trades seemingly by ordinary monsters, but actually secretly coordinated by a cabal of humans using monster accounts. The humans will take profits and then bail out, causing the monster index to crash and wiping out monster wealth. ]
[Question] [ If you look at flying animals, they usually have small tails. For instance, giant pterosaurs. Now dragons tend to be portrayed with more devloped tails. For my dragons, their tails, and the bony spade at the end of it, is their primary melee weapon. They usually either try to hit people with the spade (very lethal), or knock them off-balance (non-lethal). [![enter image description here](https://i.stack.imgur.com/pk7CDl.jpg)](https://i.stack.imgur.com/pk7CDl.jpg) I wanted my dragons to look something like this. Here's the sauce: <https://www.deviantart.com/katepfeilschiefter/art/Arrogath-327292712> Now, dragons can't have much muscle in their tails for several reasons, but I still wanted to give them usable combat moves. So, how should a dragon's controlled tail swipe be actually powerful without having much muscle? [Answer] Your dragon might use something similar to the technique of Bruce Lee's popularized [one inch punch](https://en.wikipedia.org/wiki/One-inch_punch) > > The one-inch punch is a skill which uses fa jin (translated as explosive power) to generate tremendous amounts of impact force at extremely close distances. This "burst" effect had been common in Neijia (internal martial art) forms. When performing this one-inch punch the practitioner stands with his fist very close to the target (the distance depends on the skill of the practitioner, usually from 0–6 inches, or 0-15 centimeters). The timed chaining of multiple muscle groups contribute to the punching power while being imperceptible to the attacker. > > > In their case they don't use muscles in their tail, rather use their whole body to impart momentum to the tail, like it was a whip. As long as they can produce enough force with their core, maybe even with the assistance of gravity, they don't need that many muscles directly in their tail. [Answer] The tail is an erectile organ. Humans are familiar with erectile organs. The dragons tail is such. It contains no muscle whatsoever but can be abruptly stiffened by diverting a large percentage of the dragon's cardiac output into the tail. Within the tail are actual several erectile bodies and the direction of erection can be controlled by controlling which of the 5 parallel bodies receive blood. Motions include a swipe in any of 5 directions but also a straightforward piercing thrust with all 5 organs simultaneously filled. The wings are also erectile bodies which allows them to keep a lower profile when not in use. This means, however, that a dragon using wing and tail at the same time risks hypotension and fainting. [Answer] Most of the muscle is already there. one of the reason dinosaurs evolved tail weapons so often is the muscles that move the hind leg are the same ones that swing the tail, the caudofemoralis. so the bulk of the muscle that swings your tail is there weather you want it or not. [![enter image description here](https://i.stack.imgur.com/WuTEZ.png)](https://i.stack.imgur.com/WuTEZ.png) for a tail weapon you either the sauropod solution or the ankylosaur solution. Sauropods have flexible base, a semis stiff midsection, and the rest of the tail is very flexible. Ankylosaurs have a short flexible base with a lot more more muscle and a stiff rest of the tail. The sauropod way gives you a lot of speed and distance the ankylosaur method gives you more raw power. With sauropods and the tip of their tail could exceed the speed of sound and could strike at a fair distance, they also look a lot like the tail in your image. Ankylosaurs would likely pivot the entire body as part of swinging the tail imparting a lot of power. Titanosaurs use something like a compromise between the two, with basically a sauropod tail but instead of a long flexible tip the use a shorter flexible end with a spiked lump at the end. [![enter image description here](https://i.stack.imgur.com/8iBNd.png)](https://i.stack.imgur.com/8iBNd.png) [Answer] # Butt attack Much like many martial artists will rotate their hips and torso for a more powerful attack, so will your dragon. The tail flails around as a result of that. I like [John's answer](https://worldbuilding.stackexchange.com/a/194520/21222) (+1), but dinosaurs went that way because it wouldn't be feasible for the heavy sauropods to shake their butts in battle. But your dragon is a flying creature. All it takes is one hip thrust and that tail can sucker punch a human into a 3/4 backflip. [Answer] For what it's worth, the technique behind Tae Kwon Do's strikes (which I learned as a kid) often involve quickly jutting out whatever appendage is used for striking, but stiffening said appendage at the last possible moment for added force, somewhat like the crack of a whip. Sadly, I can't seem to find a good explanation online but [Makoto's animations](https://www.fightersgeneration.com/characters2/makoto-a2.html) from Street Fighter III seem to be well-researched representations of Tae Kwon Do techniques. She doesn't have much brute strength but all of her power comes from her ability to move her limbs quickly with last-moment force. Similar to John's example above, a whip has no muscle at all, all the force comes from the muscles of the person that wields it. The same could be said of a [meteor hammer](https://killbill.fandom.com/wiki/Meteor_hammer) if you want the dragon's tail to have a weight/barbed end. ]
[Question] [ So there is a riot. This is not a normal riot; it is a uber-ultra-mega riot. The rioters are armed with the best of 21st century rifle tech and whatever they could make at home -- i.e. Molotov cocktails, flaming bricks and various clubs. The marines are under orders to peacefully dispel the riot using tasers, shields and tear gas. They are wearing 4A+ power armor which will protect them from: fire, almost all small arms fire, stabs, and beatings. It makes you stronger and faster. That said they are not invulnerable; continued fire will break armor. How to kill them with the rioters' weapons? [Answer] As a rioter, you have a few options. Some of you might have similar experiences: you are driving your car, and suddenly you realize that it's basically a violent 1-ton battering ram propelled forwards by a continuous series of explosions, and caution is advised when handling one. On the other hand, if your police is currently power armored and in the way of progress (or what you hope is progress), you might consider using your car. If you want extra creativity points: a disgruntled employee once bolted a bunch of steel to his bulldozer and rampaged through cars, houses and other street features, a power armored policeman won't be a problem. Speaking of battering, home-made explosives! For some reason you can still buy books online without repercussions on how to make explosives from household chemicals. Even if the explosion itself doesn't break the armor, its shockwave and potential spalling effect could break the servo's and policeman inside. The only 2 reasons I don't have a copy is because I don't have anything I want to blow up enough (and likely never will), and that creating explosives in your kitchen is likely to kill you with chemicals absorbed in the skin, spread through the air or currently exploding because you made a mistake in the quantities or handling them. Hit their fuel supplies and exhaust them. These power armors likely need some fuel or rather special energy sources, likely swapping batteries so they can be charged. Either hit these instead or try to keep power armor engaged in maneuvering long enough that they run out of power or fuel. You can attempt to delay them by the time they return to fuel, then taking them down when they are helpless. Hit the joints. While armored legs and joints are much more well protected than wheels or tracks ever can be, they'll likely still offer some opportunities for small-arms to hinder the system. The kneecap likely has its armor, but hitting the rear of the knee with an armor-piercing round should be able to get you results. If only the result of said policeman turning around with a limp and pacifying you, or his buddies doing it for you and not giving anyone else a chance to do the same. Remember, even if you get a shot actually hitting something as small as a kneecap from a range where power armor wont immediately be able to stop you isn't going to be easy. Civil disobedience. Its easy to find a rioter, but what are you going to do when large parts of the civilian chain that keep the policemen happy stop serving them? No more repairs to their houses or vehicles, refused to be sold any food or drink, being socially shunned, electronic services like their email stops functioning etc. The only paths forwards are either increasing violence and authoritarianism (and current orders are specifically peacefully stopping the riots where they can), or the other path is negotiation to come to a solution and stop the riots. [Answer] Lots of methods. Depends on how much prep, what the conditions are, how close you can get to them, and how many rioters dead you are willing to accept. "You cannae break the laws of physics captain!" Otherwise known as "what happens when you drop a wrench on a submarine." If you smack him hard enough then his more dense internal body parts will squish up against the inside of the armor. His brain will smack the inside of his skull. And so on. Even in perfectly form-fitting armor, an impact equivalent to about a 10 story fall is extremely likely to kill him. That's not a particularly big bomb. If he can be pushed off a 10 story building (or equivalent) and can't fly, it's bad news. Microwaves or other electromagnetic effects. One presumes there is a bunch of conducting metal in his armor if it really is powered somehow. Wrap him in copper wire and connect it the the main power supply, he's a solenoid. At the very least it is likely to melt his radio equipment and set his hair on fire. Ultra-sound likely goes through the armor. The right kind of ultra-sound (maybe not available to the typical impromptu rioter, but the ring leaders might well have it) could fry his brains. Various caustic chemicals can mess with the joints. It has to be flexible in some way. One presumes he has some kind of rubber or plastic or something making the joints. It might be as simple as drain cleaner. If you can set him on fire he may cook in the can. Does he notice right away if you put fire on his backpack? That is probably where his power supply is. Maybe by the time he does notice (Do you smell something burning?) he has to panic remove the armor. How does his power supply react to being on fire? [Answer] Do not kill them. Incapacitate them. While the marine is distracted, a rioter loops a rope around its leg. Suddenly the marine is pulled backward with the rope by a team of persons. When off balance other ropes are looped around arms, legs and head. The power armor is tied against a building with nylon ropes and steel cable, which were brought for rappelling purposes but are plenty strong. Once the marine is tied securely, a hat can be placed on his head and a mustache drawn on his face plate, and rioters can take selfies with him. [Answer] This questions reminds me of that old sea shanty, ùÖü What to do to kill a marine in combat armor, Oh what to do to kill a marine in combat armor, Oh what to do to kill a marine in combat armor, early in the morning? ùÖû ùÖü Oh pick him or her up and drop him or her off the tallest building, Oh pick him or her up and drop him or her off the tallest building, Oh pick him or her up and drop him or her off the tallest building, early in the morning. ùÖû ùÖü Oh hack his or her suit's environmental controls and turn off his or her oxygen, Oh hack into his or her suits computer and turn off his or her oxygen, early in the morning. ùÖû ùÖü Oh hoist him up in chains and hold him or her over a thermite fire, Oh hoist him or her up in chains and dangle him or her over a thermite fire, Oh hold them over a thermite fire, early in the morning. ùÖû [Answer] ## Orchestrated Evil: Great ideas everyone. I love the idea of using a car (or bulldozer). Electricity is really good, especially if you entangle the suit in conductive mesh first. And fire resistant is not infinity capacity to absorb heat, so sustained application of masses of propellant is a wonderful idea (I imagine dragging an immobilized trooper to a gas station and cooking him slowly). I do have a couple of things to add, mostly centered on the idea that if you immobilize and blind, the most powered suit in the world is useless. They also all assume a riot much more carefully orchestrated than a mere angry mob is going to be able to manage. * Suits are likely heavy. Given enough prepping, a pit filled with (name your horror - gelled gasoline, crude oil or a thick industrial substance filled with grit?) could be used - lure an armored person into falling in, then they can't see, possibly can't move, may be on fire in a sustained way, and being mobbed by enemies. * Ultra-riots mean structural damage. Literally drop a house (or multi-story building) on them. * Glue guns: If there is mass-rioting, police weapons have likely been seized. Glue guns encase victims in a mass of sticky, tough material that makes everything stick to them, make them stick to everything, would blind, jam weapons, etc. An improvised glue bomb could even be made, splattering a whole team. * Monofilament wire: You likely have some high-tech materials lying around in your near future. A spool of monofilament could be just the trick. lay out a mass of the stuff and it would be hard to spot. Get a suit to run into it at high speed and entangle them so they can't move. Various other materials and meshes could be used to perform the same trick. * As an addendum to the car and bomb thing, did anyone mention a good old fashioned car bomb? Two nasty things that get nastier together. * If you are willing to move into an industrial setting, the fiendishness goes off the scale. Lasers, cutting torches, arc furnaces, molten metal, industrial presses - all can be used to make very lethal traps. Ultimate irony would be crushing a suit of powered armor in a press molding powered armor. [Answer] It's Going to Be Tough, For Story Reasons if Nothing Else The field of riot control is based on a tacit understanding that lethal force will not be used by either side. The definition of "lethal force" in the context of someone in power armor can vary, but unless the Marine's chain of command values the lives of their troops less than the individuals in the crowd who have made specific, explicit preparations to kill them (a tough sell to the troops, as I'm sure you can imagine) the entire situation moves from "riot control" to "combat" in a hurry. The tougher your marines are (and it sounds like they are very tough indeed), the more preparation will be required to injure/kill them, and the more that preparation is going to make the individual with lethal intent stand out in the crowd (Molotov cocktails are concealable and portable, welding equipment or impromptu Panzerfausts less so). Though with strong enough armor something as seemingly fatal as "parking a truck on them" could still fall in non-lethal territory. Assuming the power armor lacks "point defense" equipment (reactive charges, "electric fencing", chemical dispensers etc.), it would be possible for the rioters to blind/swarm/immobilize/otherwise render combat ineffective the marines and trap them in their armor. The design of the armor itself can't be ignored in that case; armor intended for the battlefield would be designed to resist long range weapons fire, while armor intended for riot control would be designed to prevent immobilization, with extra paneling to prevent insertion of hands, crowbars etc. into vital areas (seen today in the difference between ballistic plate carriers and full-body riot control armor). The focus on incapacitation would prevent the conflict from moving into lethal territory, within which it seems the marines would easily win if only through liberal application of the "drop trooper's handshake"--grabbing an exposed body part of an unarmored individual and giving it a good squeeze (ouch!). It's this answerer's opinion that any exploited weaknesses will need to be strategic ("there's too many of them") or zero-day in nature ("we never thought of this"). Something as simple as paint sprayed over a visor could do the trick. But in the arms race of technologically advanced government vs. mildly organized rioters, with both given equal opportunity to prepare and in a (generally) less-than-lethal context, it defies belief to think that the rioters will win. [Answer] Use tactics! The thing is I don't see this as a problem since a marine in power armor is not superman and his training and tactics would mostly be the same as without PA. The biggest problem is this Sure with PA you can be all parade like and stand in the middle of the street looking regal and shiny. But once bullets start flying that marine's training is taking over and he is diving towards cover and using tactics that is drilled into him to resolve the situation. Marines would just do what they know to achieve their goals. The added protection of PA can of course work in certain situations but would mostly be balanced by the risks involved since any officer can quickly and accurately optimize a course of action. Example: Rioters are attempting to break into a position you are ordered to defend. That place might be your base or the residence of the president or Dunkin' Donuts for all that matters. As a soldier you obey orders. Anyway the rioters are coming in with clubs and flag and knives...etc. That situation you are still in danger if you engage them in CQC but still your own PA offers enough protection that you can engage the closest and most daring offender. You have order to peacefully resolve the situation so your course of action is to relay on your PA and show enough controlled aggression to deter the rest of the crowd. But if you are just protecting your thing and bullets start flying you dive behind the sandbags, shoulder your M16 and laying down a hail of fire at the source of incoming fire before you can even realize what happened. You are a soldier. That's what the army drills into them. So. Even with the idea of "The marines are under orders to peacefully dispel the riot using tasers, shields and tear gas" Only works as far as the rioters do not bring their own automatic rifles or at least use them. If the rioters start shooting you really can't stop any soldier in the world from returning fire. So. What you have is a skirmish type of situation. Where the rioters attack the marine and both sides have their safety off. Of course marines won't just relay on small arms because the does not deal in anything but overkill. Citizens or your local variety terrorists once the bullets start flying the soldiers are hopping into their tanks, IFVs, and ordering a drone strike but I digress. Anyway I'm not sure if that is a frame challenge or not but I just think this is the most logical course of action for soldiers anywhere every single time. With that being said you can just use stuff like: Armor piercing rounds, grenades, sustained fire, higher caliber rounds...etc. Again coordinating the attacks and trying to isolate small groups marines in a building then just shooting thousands upon thousand of rounds on them is pretty much the only thing you can do. You are not gonna send your agile PA armored melee units to counter them. So. Take a page out of the army's book and just throw absurd amounts of bullets at them. If a bullet does 1% damage to them you just need to fire a thousand at them. But without a command coordinating those attacks and officers on the ground adapting to the battle the marines would 9/10. But again I digress. So. It all boils down to not what technology are you using but what tactics are you using. Sun Tzu would still be applicable here as he ever was Lastly I'm not sure about the rest of your story or world so I'm not judging. But if this is the US then don't think the US army can be called upon to intervene in internal affairs even for peace keeping stuff. But I could be wrong. [Answer] ## ‚ö° Electricity ‚ö° Overload those tasers, metal conducts electricity right? And that wasn't explicitly mentioned in the prompt, though it isn't the rioter's weapons but the marines'. Pikachu - thunderbolt! ]
[Question] [ If I have spaceships that are firing some variety of cannon at each other - MAC, laser, particle cannon, doesn't really matter the type - at extreme range, then even if the gun itself were somehow perfectly precise, the targeting system on which it is mounted is not. If the gun is spinally mounted, the ship will need to turn towards the target, and there's some imprecision there. If the gun is in a turret, there's only so much the aim can be refined with engineering limits. So my question is: With MODERN technology, how precisely can we aim at a target? Even if I have a gamma-ray laser that can vaporize a target at a range of several light-seconds, and the target can't maneuver in time to evade, it's pointless if I can't HIT the spot I'm aiming at. Having an idea of what we can do with modern tech will give me a lower limit for how accurate a futuristic warship would be. [Answer] # Depends how long do you need to orient the weapon on the ship to damage it. ### If you need the beam to hold for a long time (>1sec), or your using railguns: I'd be looking at the accuracy of surveying tools like Theodolites. [Here's one on eBay](https://www.ebay.com.au/i/164287008672) than can do 10 seconds of angular accuracy. That's (10 / 60 / 60)'th of a degree. 0.00277778 degrees. That's about 5cm accuracy at 1km. 1m accuracy at 20km. It could hit a 100m ship at 2,000km. That's just what the ebay one can do. Assume military grade is twice as accurate. I've found [references](https://www.dynapar.com/knowledge/encoder_resolution_encoder_accuracy_repeatability) to encoders able to do 5 seconds of accuracy. So a 100m ship at 4,000km. ### If you only need to hit it with a laser for a fraction of a second, or pulses are fine: We can measure time much more accurately than we can measure angles. So lets measure time instead and use time to measure the angles very precisely. You can achieve incredible accuracy using rotating mirrors and a static laser fired at precise times to send pulses in exact directions. This is a process we use at my work to build laser scanners for surveying mines / crime scenes / car crashes / etc. You can use it to send gamma ray death beams nanoseconds long. The process is to start rotating your mirror at a slow, steady speed, put the laser on at low intensity and record exactly when it hits a sensor (inside the gun housing). From that calculate the exact rotation speed and phase of the rotating mirror. If your mirror is doing 1rps, and your computer / sensor / etc is capable of running at 5ghz, you can turn the laser on and off very precisely at the exact angles you need - you can get your laser accurate to 0.000000072 degrees. That's accurate to 1mm at 1000km. (Could probably do laser eye surgery at 1km). Hit the moons surface within 30cm. 1m accuracy at 1,000,000km. Hit a ship 150m in size in orbit around Mars from Earth orbit. [Answer] More accurate than you might think possible Let's look at a surprising science: photography. When doing photography of objects that are distant, low light or both you need to have a longer exposure to make the image bright and detailed enough. But anyone these days can tell you that making a picture in a dark room is difficult. You need a steady hand as well. If you've ever worked with telelens cameras to photograph a distant object, you also know the tiniest movement can make the desired object disappear. Now lets look at one of our most long distant camera. The Hubble telescope. Space is unimaginably big. Pointing it at different stars with a zoom that will give us enough resolution requires an incredibly stable camera. Unfortunately the camera us hurtling through space at huge velocities. For the exposure required you still need some tracking for the most minute changes to keep the camera steady and focused. They even struggled with this at first and made it so it could turn even slower to track more and more distant and low light objects. To quote NASA: The level of stability and precision that the FGSs provide gives Hubble the ability to remain pointed at a target with no more than 0.007 arcsecond of deviation over extended periods of time. This is the same as holding a laser beam focused on Franklin D. Roosevelt’s head on a dime roughly 200 miles away — which is about the distance from Washington, D.C., to the Empire State Building in New York City — for 24 hours. If you can point a camera with such small tracking to other stars and planets in other solar systems, you could fire there as well. Mind you, this was made with the end of 1980's technology and since somewhat improved, but if we build something new with today's technology we'll probably make it much better again. ]
[Question] [ I'm having a tough time coming up with good weights for my weapons to allow me to calculate what swords would take longer to swing, for example. Here is what I have come up with so far: ``` Dagger: 430g - quick attack speed but not as much damage. Sword: 800g - standard attack speed standard damage. Longsword: 1500g - slow attack speed but high damage. Bow: ?? - standard draw speed?, standard damage? Longbow?: ?? - slow draw speed?, high damage? ``` I can't think of any other weapons which offer a different fighting style, but don't step away from the classic fighting experience. My game is an Fantasy MMORPG, but a very small portion is PVP. It kinda follows Sword Art Online (the anime), with it's atmosphere, architecture and weapons, but the gameplay itself is nothing like it. I don't want too many weapons as there will be many materials used to craft these weapons which would affect the weight and benefits, but if there is a clear option which you think I should add, please do let me know of course. I just need these weights as a base starting point, and then I can adjust the weight/speed and damage depending on the fictional material used to make the weapon. I had absolutely no idea what to do with the bow(s), ideally I want 2 different types of bows to allow for a more ranged gameplay (pun unintended( but I don't think they are that different irl, so I might just stick with the normal bow. Thanks for your input! [Answer] I will speak in broader terms, including carrying capacity into the question. Indeed, the two are closely related, and in the end, it's more about the number of items one can hold than the exact weight one item is. But I will getty to that point later. ## Adjust the weight according to the fight intentions your team wants to give What I fear is that you're reversing priorities between core gameplay features and feelings vs flavor. You should focus first on strengths and weaknesses of your weapons, speaking in terms of number of hits to kill, range, speed, special abilities, and feeling they should provide, then to the weapon's weight. Since people cannot carry the sword themselves, weight cannot be felt, and therefore it should be laid out on the background after what they can see, hear or sense (with the controller's vibration). Feeling is more important than a number on the item's description. It goes into the overall look and feel of your game and the intentions you want to give. If this is a heroic fantasy game, boost up weapons's size and weight as your characters are strong, sweaty heroes, not your average farming Joe. If your avatar is living in a dark, realistic world or are weak compared to monsters, decrease them instead to make them look more frail and inefficient against what's to come. It all goes down to the intention of your game. Recall that the intentions should be thought on the whole team level, especially the artists since they will draw how characters and weapons will look like. Marking all your weapons as light and then noticing all artists drew bulky heroes wielding 5 meter swords will make you feel you lost time :). That's the game designer's job to ensure everyone is on the same page. ## Balance the weight according to the drop quantities and character type average carrying capacity The idea is to not focus on the sole weight, but think it as a whole. For instance, how scarce or plentiful the drops are? Do players can acquire equipment only through crafting (gaining materials from dungeons/jobs). Do you want your players make constant conscious choices over what to keep (Very important if you have lots of single use items or a durability system), or do you want them to be more carefree and grab everything they can find, hack-and-slash style? This, in overall, will determine how much items one should be expected to hold. Often times, you will notice that melee warrior characters will have more carrying capacity than mages or rangers, yet they can carry about the same amount of their class's items because their equipments weigh more. It's partially because if they can carry more, they may become some drop mules which is rarely wanted. However you still want some difference in feelings (as per the first section). Hence, adapt weights to how many items should one be able to carry! ## Follow the marketing strategy If your game is following a free-to-play model, you'll probably be influenced by the editor/producer, asking you to restrict how many one can carry items, in order to sell interesting bonus inventory packs. This can be annoying as it brings down your creativity, but sadly, a person can't eat their own bytes of virtual bread from their games. You should take it into consideration and reduce voluntarily the carrying capacity or increase your item's weight in order to incite the buying of such packs. Still, as you are responsible of the quality of the player's feelings, don't overdo it and don't hesitate to tell that it isn't possible without hurting too much the player retention on the long term. Then, in order to not reach a dead end, try to offer an alternative you can more easily negotiate on. ## Playtest This is a kinda all around solution to all game designers issues, but it works, and really well actually. If your game is not yet in a playable stage, you can make a paper version of your game focusing on drops and weights. For instance, make a fake run through dungeons, and ask which item your testers want to keep, following your set weight rules. Then take their feedbacks and feelings about what you have made. If you don't have anybody available, prepare some tables and play with values around for an estimated game run, and get others' quick feedback (it's always important). It's not as valuable as playtesting, but it formalize things and can give others a rough idea of what to expect, improving their own image of what the game would be. ## But most of all, keep things simple and focus on gameplay Unless your game has one of its pillar be inventory and drop management A.K.A. survival games or simulation games (which, given your description doesn't seem to be the case), you shouldn't spend too much time estimating exact weight/and or size of real world counterpart. Players tend to overestimate the weight of items and even more one's real carrying capacity. Peck, have you seen someone wearing 4 plate armors, 3 bows, 6 (unbroken) potions, 6 swords, spears and shields, a quiver containing 150 arrows and a pouch holding 20 000 gold coins? And yet in games, unless you put visual indicators like in [Death Stranding](https://fr.wikipedia.org/wiki/Death_Stranding), almost nobody will think about it. At worst they will give a smile thinking about their character carrying this much, which isn't even a bad thing! What I mean is that it goes all into the suspension of disbelief. And you can safely retreat behind it, especially since you won't have a lot of time designing your MMO. Yes, you probably won't have a lot of time. Remember, MMOs are one of the most expensive type of game projects in the industry (networking alone multiplies at least by 2 the cost), so you will have a lot of matters to attend to. And since your game involves even a little bit of PvP, you will need some time as a game designer to balance character archetypes and powers. Time that doesn't involve weight calculation unless it impacts the battle gameplay, in which case simulation may not be better than pure-gameplay values. After all, players are more concerned about a balanced experience than that a [real viking sword weighs less than 1 kg](https://www.youtube.com/watch?v=0QDPU0itinU) and in your game it's 5 kg. [Answer] ### 0.9 - 2.3kg for standard bow. 0.9 - 1.8kg for long bow: > > The physical weight of a traditional longbow is somewhere in the two to the four-pound range while a traditional recurve bow is between two and five pounds. > > > [![enter image description here](https://i.stack.imgur.com/vXguc.png)](https://i.stack.imgur.com/vXguc.png) Source: <https://bosstargets.com/how-heavy-is-a-traditional-bow/> That link goes into all sorts of discussions on bow weight, eg attachments and such - I didn't know that heavier bows prevent fatigue from the vibration, for example. [Answer] For a game, keep it simple. Especially if PVP is not a big part of your game. You can have attack speed and damage, and ranged or no. Simple variables. If you want more variety in weapon types (to excite your players!) go ahead and have it, but ultimately it will be the same variables to consider when you have a fight. For example a war hammer might be even slower than a longsword and do even more damage. A dagger faster than a sword and less damage. ]
[Question] [ Numerous answers to my [last question](https://worldbuilding.stackexchange.com/questions/189253/30-year-groundhogs-day-how-to-increase-the-worlds-technology) suggested the best way to anonymously share future data was to hack the limited protection of early 90s internet. I know the first publicly available BBS had just came online in 1989, so with enough money, our time traveler can access them to post data. My only question is: how can he do this anonymously? Given the importance and magnitude of data our protagonist has to share, most people across the world are going to want to know its origin. Anything he shares will likely result in top level government effort to trace it back to its origin, he wants to ensure they do not succeed. Our protagonist is willing to use any exploit to hide his identity so long as it doesn't do serious harm to others, but does not want to destroy systems or use a killer poke. Given that he appears to be five years old, most social engineering approaches are going to be out as well. While the protagonist can eventually take back as much knowledge or hardware as he requires, I'd like a strategy that doesn't require extensive hardware or more knowledge than he could reasonable be expected to memorize if possible, as that allows him to do it sooner. Finally an approach that he can pull off without expensive 1990 hardware would be ideal, to avoid the difficulty of convincing someone to spend that much money on a 5 year old. But he is willing to arrange to win a small lottery if necessary to fund buying more expensive gear. [Answer] Building off a response from Ash: # With a Single Custom-made USB-sized Interface Ash went into an excellent amount of detail about how to bring back a bunch of tiny computer chips and scatter them to the winds and make finding you an impossibility. I read through your original post o nthe limitations and goals of the time jumping, and I think it can be made much simpler if you do a bit of prep-work in your 30s. ## Note: This Will Not Be Possible Until Your Second or Third Run The first step is to figure out exactly what systems you are going to hack into, how, and at what time. This will have to be done as a child and you'll need to write it down and save it so that you can write the program that automates the process in the future. Once you reach your 30s, you use the most advanced miniaturization tech you can get your hands on to build a specialized circuit-board that will connect to a standard phone jack and then execute your program. Your program will then automatically hack into every system that you've designated and dump all the data into those systems. The key to this is that it needs to be something you can plug in and then walk away from while it spends hours uploading data to a variety of systems worldwide. This also only works once, because you're going to inspire the growth of security protocols the world over (some of which may be in the papers you publish). When this is done, the butterfly effect takes over and you will never be able to assume that you can hack anything anonymously again. You do, however, have this one free shot before the world changes, and thankfully you're in the 90s so it's a lot harder to get caught than people seem to think. You've developed a simple one-off device that you plug in and then walk away from, so the second step is to find a place that you can plug it in without being surveilled. Thankfully, it's the 90s, and you've spent at least 50 years casually (or actively depending on your level of paranoia) thinking about how the government tracks people. You find a place to plug in your device that's close enough to your home that you can manage to get there at 5 years old (it's the 90s so kids even at that age have a lot more free reign of the outside world), and you never deal with it again. The beauty of the idea is that it can't mess up. Once you manage to pull this trick off the first time, you can do it exactly the same way every cycle because you won't have changed anything until after you plug in your device. # Major Limitations As I can see it, there are a few major limitations: ## You have a very limited amount of data you can upload in one shot like this Bandwidth limitations of 90s what they are, I don't think it's reasonable to assum you can upload more than 1 GB of data TOTAL before your system get's shut down. This is not 1 GB per system you're uploading to either, so unless you're building in a powerful virus designed to take over the system and then copy the data to other systems (not a bad idea come to think of it), each of the systems you try to connect to will reduce the amount of information can send to each of them. ## You can still get caught by paranoid time police Ok, so time police don't exist...yet. If you introduce the verifiable fact of time travel, there's a good chance that someone will invent time police to try to find you. They will realize that someone is sending scientific papers back in time, and they will also realize that they will grow up to become time police once it comes out that papers are coming back in time. They will then send themselves coded messages in important scientific papers in order to find you. ## You will forever change the state of internet security and may make future hacking impossible I don't know for sure that I need to go into this, but I'll mention it anyway. If you want to have any hope of advancing the future, you're going to be including papers about digital technology including the most advanced security protocols of the modern era. Even if you don't put forth the best security protocols of the modern era, they are sure to develop their own after your sophisticated and wide-scale hacking spree. [Answer] ### With some untraceable, tiny modern tech How small can you make a computer that can talk to a 1990s BBS system? This is the PSoC 4000, it's 1.45mm x 1.45mm by 0.42mm (for the Americans - 1/16th inch x 1/64th inch. Think smaller than a grain of rice).: [![enter image description here](https://i.stack.imgur.com/qGcYc.png)](https://i.stack.imgur.com/qGcYc.png) It's basically a tiny 32-bit computer on a chip the size of a pixel on printed paper at 1990s tech. Runs at 16Mhz (5000 times faster than a modem of the age), and comes with 16kb of storage. It's [$73](https://www.google.com/aclk?sa=L&ai=DChcSEwj-laS_j-HsAhXFuZYKHQbpAP0YABArGgJ0bA&sig=AOD64_3NcCj8os_1meGDZ2pAZeKsPScqsA&ctype=5&q=&ved=0ahUKEwi3uZ2_j-HsAhUDjuYKHRGlBOEQ2CkIlwU&adurl=) Including development and programming tools. To connect that to a phone line you'll need a very simple circuit, all of these parts existed in the early 1990s, and are available today: * A battery of some kind. * A voltage divider (2 resistors) to get the (comparatively) high voltage phone line down to something which can be measured by the low voltage of the chip. * A transistor, to get the low voltage signal from the chip up to phone line voltage. * A "play" button. (or you can just attach the battery and have it auto play) * Terminals to attach to the phone line directly. * Mount them all on a simple circuit board, which you can make at home using [pen](https://www.ebay.com.au/itm/PCB-Circuit-Board-Etch-Acid-Resistant-Pen-/121133836438) and copper and low-strength acid. Bit of home soldering to mount the parts. You can get it made professionally for only a few dollars, but the lower quality you get from making it at home will help it look like tech from the 1990s, (minus that one mystery component). A simple modem program compatible with the tech of the day will easily fit into 1kb, a [decompressor](https://github.com/pfalcon/uzlib) can fit into 1.5kb, leaving 13.5kb for compressed text, so you should be able to get about 45 pages of text into this tiny chip (30 lines per page, 79 characters per line, 8:1 compression ratio of typical English text). Build the circuit. Paint the chip pure black. Test it. Then travel back in time. The simplest way is to connect your device directly to the phone line and then hit play on your tiny modem (it can dial the BBS directly by simulating either pulse dialling or DTMF tones). You could also connect a speaker and microphone directly, but that makes sounds which can attract attention. When you're finished, bend the board until the chip detaches, and throw it in a fire. The circuit board is not beyond the tech of the day so can be thrown in the garbage consequence free. Extra credit idea The microcontroller can be powered by the phone line via a voltage divider (another 2 resisters). So make 10 circuits, and get 10 blasting caps. Get 10 antique phones. Program the tiny controllers to sit idle for a month after being powered up, and then randomly start trying to dial the BBS and upload the package. If the package upload succeeds, send power to the blasting cap which is a tiny 1mm x 1mm black dot glued to the blasting cap. Travel back in time, and donate these phones to various charity shops. They'll find their way into various homes, 1 month after being plugged in, they'll start trying to upload the data to the BBS, when they've succeeded, they'll explode (the explosion will be small and will be unlikely to injure someone unless they're very close). Some poor housewife will be sitting there having a calm afternoon tea, and the phone she bought for cheap from the thrift shop last month explodes, then later that day, FBI kicks in the door. You've had over a month to get away, all the security footage of you donating phones has been taped over, all the investigations lead to confused housewifes with exploded phones, and the forensic investigation is unlikely to find the tiny black dot which housed the modem and the sensitive information. And if they do, they're unlikely to be able to hack past the read-only mode and enter programming mode, and even then, they're unlikely to link it to you. ### Really don't want to take any modern tech back? Another way: * Set up an anonymous BBS system in the present day. * Buy from an antique shop: + An old computer of the era + an old 4800 baud modem. (or similar. [A 9600 baud modem might be too modern](https://en.wikipedia.org/wiki/Modem#Overall_history)) + an old Walkman-like sound recorder * Setup a recorder to record the sounds your modem sends down the line (filtering out what their modem plays back, and the sounds from the phone company). * Use the old computer to upload your data to the BBS system. * Once the upload finishes - stop the sound recorder. * Travel back in time. * Go to a remote payphone late at night. * Wearing gloves, dial the BBS number. * Hit play and put the speaker up to the microphone. * Once the recording finishes - walk away with the tape. * Burn the tape ASAP. [Answer] Start by hiring an assistant who at least appears to be a grown up. A few of the steps in this process are going to require in-person interactions which might be hard to pull off while looking like an unattended five year old. Your assistant should be female and approximately the correct age to have a five year old child. It wouldn't hurt if she were a little nerdy so that her interest in computers is not surprising to others. For full anonymity, she should have been chosen before travelling into the past, from a historic report of the fatalities of an upcoming airline crash or train wreck. Once you are done with the information distribution steps of this plan, your final step will be to make sure she gets to her plane/train on time. If allowing her to die as history demands is outside of your moral code, you can rescue her at the last minute and take her with you back into the future, as long as surviving witnesses recorded her getting onboard. Now for the information distribution. Research the names and mailing addresses of every 1990 BBS owners using a mixture of future historic records and 1990 phone books. Provide your assistant with cash to buy a computer, some postal supplies and a lot of 1990 style floppy disks from local stores. Record your information on the floppies and then just mail them, along with hard copy printouts to the BBS owners. Any attempt to investigate the origins of the information might get as far as the public post box into which the letters were dropped. If the detectives get a luck break, they might find the stores where the envelopes, stamps and floppy disks were purchased. In the unlikely case that they somehow trace these cash purchases back to your assistant, they will find that she died in a disaster which could not have been predicted before hand. From there, you can depend on age-ism to obscure your involvement in all this. Five year-olds can get away with just about anything. Apparent innocence and being cute are an amazingly powerful combination. Addendum... Depending on the nature of the information which is to be distributed, you can further protect your identity by giving the investigators a false trail to follow. In addition to your assistant, find a few scapegoats using future history records and phone books. These people should all have specific characteristics which make them interesting to the detectives. Maybe some of them have relatives who work in industries closely related to the information. Others might have criminal histories and radical beliefs. A few social activists and a Russian immigrant would round off the group nicely. Have your assistant contact and hire each of them. Have her pay them cash to help her copy floppies and stuff envelopes. You don't have to attend any of these meeting. Now the investigators have a fully staffed terrorist cell with an accidentally killed leader to keep them busy. With all that intrigue to chew on, they won't need to look further for an explanation. [Answer] Well, there is a lot of (sometimes badly written) Russian Sci-Fi on "how to fix past things with time travel", where most involve "not being caught by KGB" (or what was its name in the era). I am borrowing heavily from those. # Use (older) spy techniques Record the data is some way, stash it somewhere safe in the past (you have the time, since no one knows you are stashing something), alert your government contact / journalist of your choice / local police officer. If you want, the alert step might involve BBS, but should not. The good thing: the actual live communication is short, less options to be traced. As far, as I understand USA, you can just hook a modem to a phone in a phone booth in the middle of nowhere, send a short message, unhook the modem, and drive away. Further sources of inspirations would be the communications operations by some intelligence services done before small electronics kicked in. Read the memoirs! Or some mafia transactions of the kind "let's exchange this suitcase with money for this suitcase with cocaine and let nobody get shot". # Efficient recording Since your protagonist is stashing a memo (about 9/11, Kennedy assassination, etc.), they might just write it down. As long as no one is there to catch them and to demand a comparison of handwriting in court, this is Ok. Extra bonus for some too good or unusual typesetting. (For example, folks from 1930s would be rather surprised to see modern bleach-white paper printed with a laser printer. They will be able to find out, this is not printed in their-modern way, trust me. Or just take a look on differently-printed paper under a microscope.) If the memo is openly stating "I came from the future to prevent XY, this adds credibility. You might use some data storage, you know, exists in the era. Such as a set of floppy disks or [microfiche](https://en.wikipedia.org/wiki/Microform). The best approach I have seen, was to: 1. Use [stenography](https://en.wikipedia.org/wiki/Shorthand) for a compact writing (requires learning it, but helps a lot. You can also use computer-based typesetting, there were some approaches for that.) 2. Fake foreign handwriting when doing so (hard, might be unrealistic, so this is optional) 3. Photograph the written sheets on a usual film camera (requires some fiddling, but is generally doable) 4. Place the film in the hideout from above 5. Alert the KGB chef, his package lies in the secluded place. Basically, your recipient would be responsible for picking the film up, developing it, printing the frames, decoding the writing, acting on US missiles in Turkey (or what not). Guess, what is the hardest part? Again, if a computer might play a role, then a (modern) one in 1 and (contemporary) one in 5, with a modem and somewhat secure / pseudonymous connection. You do not want the session to be fully anonymous, it suffices not to be caught. Hence, "random entry points" cross the country might help. Or hacking. Oh, the hacking! # Blue boxes In the 60s, there was a lot of action in the telephone department. Some custom-made devices could play the role of the phone company equipment and do magnificent things. Of course, they were illegal. For example, a [blue box](https://en.wikipedia.org/wiki/Blue_box) allowed you to call long-distance for free. Using such a device for the transmission would not throw a large, state-sponsored intelligence division completely off-track, but would help to slow them down. There was/is a strong community around the colorful boxes, so some connections and a lot of googling in their time would help the protagonist. ]
[Question] [ In my world, humans have the innate power to fly. This is a supernatural power, like superheroes, so there's no scientific explanation. However, they still need oxygen to breathe, G-force is still a consideration and other physical limitations remain. I'm interested in what these limitation would be, supposing that humans are not using any technology to boost their flight capabilities and they have no speed or weight limit? Here is a list of questions but it's in no way exhaustive: * What's the maximum G-force a human could sustain? Roughly 75G * What's the maximum altitude they could reach? I think 8000m because of oxygen but maybe temperature would be a bigger problem. * What's the maximum speed they could attain before damaging their bodies/dying, assuming acceleration is not too hard? * Does air friction become a problem at a certain speed? I'm assuming yes. [Answer] Temperature: As altitude increases, temperature decreases, by about 2 degrees C per 1000 feet above sea level. Temperatures will dip below freezing at around 7,500 feet up, so you'd probably want to stay quite a bit below that or risk frostbite. Especially with windchill, any exposed skin will be at risk. This temperature change occurs relative to ambient temperature at the ground, so you could go a bit higher relative to sea level if you're in a very warm area, or if you're in an area with a high elevation, which will be somewhat warmer than just air at the same elevation. Oxygen: The amount of available oxygen decreases with altitude. The [FAA requires pilots](https://www.aopa.org/training-and-safety/active-pilots/safety-and-technique/operations/high-altitude-flying) to use supplemental oxygen at cabin pressures above 12,500 feet for 30 minutes, on the assumption that the plane will immediately dive to an altitude with breathable air pressures upon loss of pressure, and at all times at cabin pressures above 15,000 feet. You begin experiencing notable reductions in performance from hypoxia [above 11,400 feet](https://www.skybrary.aero/index.php/Hypoxia_(OGHFA_BN)#Complete_Compensatory_Stage.2C_1.2C500_-_3.2C500_m_.285.2C000_-_11.2C400_ft.29), though the [time of useful consciousness](https://www.planeandpilotmag.com/article/flying-high-unpressurized/) remains indefinite until 15,000 feet, beyond which it begins rapidly declining. G-force: This is mostly a non-issue - so long as you're not speeding up, stopping, or turning too quickly, you can keep your G-forces at manageable levels. The biggest limitation will be your turning radius at high speeds. Top speed: Since these people can accelerate without bound, their maximum speed is theoretically unlimited. Once breaking the sound barrier, however, there will be significant heating due to air resistance, as pressure increases dramatically once you are flying into your own shockwave. According to [this question](https://physics.stackexchange.com/questions/43768/after-what-speed-air-friction-starts-to-heat-up-an-object), speeds in the range of a few thousand km/h could cause heating in the range of hundreds of degrees C. Air density decreases with altitude, however, so you will be able to go faster at higher altitudes. At any rate, the sonic boom when breaking the sound barrier will also be quite unpleasant, so you probably want to keep it under Mach 1 (1234 km/h). I'll also mention that even windspeeds in the low hundreds of km/h can be very damaging, uprooting trees and leveling homes. Unless you're wearing specialized skintight clothing, whatever you're wearing will likely get ripped to shreds if you're flying faster than perhaps 300 km/h - I hope you don't mind arriving naked. Overall, humans without any special equipment might be limited to flying at sub-sonic speeds under 1000km/h, and may only be able to fly at a couple of hundred km/h comfortably. Top altitudes will be about 5000 feet, depending on local climate and geography. With warm clothes and flying at low speeds, one could perhaps get up to 15,000 feet in altitude before availability of oxygen starts to become a big issue. Otherwise, the limiting factors will be air resistance for speed, and temperature for altitude. Since these work oppositely (altitude makes you too cold, speed makes you too hot), you might be able to balance these somewhat to go faster at higher altitudes, but you'd probably need to be spinning constantly like a rotisserie chicken (since only your front side is being heated) and you'd risk burns or frostbite if the temperature balance didn't work out just right. [Answer] Orientation: when earth isn't visible pilots can't reliably determine their height, speed and and bearing and must rely on instruments. Unaugmented humans would get lost in clouds easily, with risk flying into ground at high velocity. Even without clouds, over monotone bare rocks or calm water it can be hard to judge safe flying height. Without navigation experience it is also possible to fly in circles and starve. ]
[Question] [ When designing something really big, which can be compared in size with at least a planet, one problem seems to be unsolvable. The problem is how to fight the gravitational force that will collapse everything that is huge enough. The idea is to come up with a way to do gravitational shielding in such a way to build structures of arbitrary size. The structures I am talking about are something like [The City](https://blame.fandom.com/wiki/City) from [Blame!](https://en.wikipedia.org/wiki/Blame%21). The main challenge, in my opinion, is to make this shielding to work with known physics. This means that unobtanium is not the way to explain it and neither is magic or unknown technology([as it is done](https://blame.fandom.com/wiki/Megastructure) in the manga). At first sight, the main candidate to be the form of matter that has antigravitational properties is antimatter, but today it is [almost certain](https://en.wikipedia.org/wiki/Anti-gravity#Fifth_force) that it is not the case. From all the sources that I have read, it seems that the [theory does not entirely forbid](https://aip.scitation.org/doi/pdf/10.1063/1.3327545?casa_token=c8xShsLHKd0AAAAA:OZII_Vy1yi5lYCQPaxGn9vR0M33J9L93mUc3SKtu9CNpyPEljRy_HjyIdrgcIOhkOV19qhVAVYig) the existence of antigravitation, but all observations suggest that antigravitation does not exist. But here the question is to come up with a realistic explanation of antigravitation which will not obviously conflict with modern physics. [Answer] Dark Energy According to science, the expansion of the universe is [accelerating](https://en.wikipedia.org/wiki/Dark_energy#cite_note-paalhorvathlukacs-28). They don't know what can cause this, so for now they use dark energy to explain the unknown phenomenon. There is evidence that something is active, so whatever it is, it's plausible to be used scientifically. What I read here is that there is an energy able to push whole galaxies apart at an increasing rate. That opens options for a form of anti-gravity. Putting dark energy inside structures might be able to push against material, negating part of all of the gravity. As an addition, I would use not solid structures but intentionally use hollow lightweight structures to decrease the gravity from the overall structure. [Answer] ## The best way is to not have to develop new physics, or break existing physics. Use what we know instead. So perhaps an engineering solution instead: ie. use existing physical principles but just think big or a little out of the box. For instance: * Active Support - Structures built today are what you would call 'Passive Support'. This is usually simply compression or tension of building elements, however there are limitations to this that limits size. But if you add energy ([Active Structural Support](https://en.wikipedia.org/wiki/Active_structure)) to the system you can create much larger structures, such as [Space Fountains](https://en.wikipedia.org/wiki/Space_fountain), [Launch Loops](https://en.wikipedia.org/wiki/Launch_loop) and other systems that require energy via fluid or cables to counteract their weight. This enables structures that are colossal, with the constant input of energy, and all you need is to find the energy and to dissipate their heat. * Centrifugal force - Why not have the city orbit, much like layers of a dyson swarm around a star, but this time around a planet. Or [similar to an orbital ring](https://en.wikipedia.org/wiki/Orbital_ring). The rings have cables / mass inside that rotate in orbit, supplying the outward force necessary to suspend the city. Again, just a matter of adding energy to counteract friction in this case. * Counterweight - Having large asteroids in Geosynchronous orbit with tensioned cables to 'hang' the city on. This is similar to the [Space Elevator](https://en.wikipedia.org/wiki/Space_elevator) concept, perhaps using carbon nanotubes as a material to enable suspension. There is in fact no limit to the size of your city here. * Atmospheric Pressure - [JP Aerospace experimented](https://en.wikipedia.org/wiki/JP_Aerospace) briefly with suspending a 'Dark Sky Station' ie. city in the sky as a stepping off point for high-altitude airships. You can have extraordinarily large helium or hydrogen balloons that suspend the city structures. These ideas are actually grounded in reality, and when multiplied to the extreme there is no reason why they cannot form large suspended, multilayered kilometre high cities. The engineering challenges need to be overcome, but this is nothing compared to trying to invent new theories of physics that replace proven existing ones. [Answer] # Electromagnetism. To prove your construction as plausible I dont think you need anti gravity. You just need to explain how a structure thousands of kilometres in size doesnt collapse on itself. You need a force to offset the compression force that limits the size of such structure. Rather than anti gravity, I propose good old proven electromagnetism. I present <https://en.m.wikipedia.org/wiki/Space_fountain> as an example of such a structure. Thousands of tiny pellets shoot around at high speeds, interacting with electromagnetic coils within the structure in a carefully controlled, monitored, way, applying tension or compression forces through the pellet stream, rather than through the material the structure is made of. The concrete and metal in such a structure is not structural. The structural members are actually moving pellets. And the limits to how big you can build is how much power you have to power your coil guns at the base. Using such design you can have a structure made of metal and concrete span thousands of kilometres without stressing the concrete or metal to breaking point. If the power cuts, the structure can stay standing for a few hours (see wikipedia link), but a permanent blackout will destroy the structure. [Answer] I don't think(but might be wrong) that this is possible with your technology level. So, here's a way to make something that most casual readers won't understand but assume that it works for almost any application you happen to need. Step 1- your purpose(antigrav something) Give it a fancy (or not) name that basically sums up the purpose of the machine, and maybe slightly suggests the technology used to make it(graverator, gravity + generator). combining 2 words makes for catchy names. Step 2- How does it work?(You don't know, but the reader doesn't know either, so they'll take your word for it) Whenever explaining the way your graverator works, have your scientist man begin rambling off an explanation at least a paragraph long, maybe two and hope the reader skips to the interesting parts later. It's a good idea to include something about atoms, nuclear power, quantum whatnots, or whatever sciency stuff you can find on wikipedia. If your reader does read it and recognizes it as BS, the worst that could happen is they give your story a 0 star review. Step 3- there has to be hazards(maybe a big red button as well) whenever making experimental technology, there's always some thing that are unknown. even with old technology, there are things that can go wrong(like when your car breaks down). maybe add a few sentences to said scientist man's explanation about how the graverator might reverse the effects and implode your super-structure. Not sure this helps, but i think its a pretty good catch-all for technology you need to make up for your story. [Answer] There are a few option´s / ways you can solve this problem. Just make some Physics up By far the easiest way is to make something up. Often times when writing something like this, you will notice that it just cant work with or known Physics. But as they say, there is always new Physics. So you could say "We found this new Physics that lets us do X". So for example, in your world the "Gravity Particle" is discovered. it has some weird properties but also some sort of charge. Which can either be +1 or -1. By Inverting the Charge, you effectively make Gravity a Repulsiv force. But this can only happen in a Special field that well Inverts the Charge. Dont use Gravity If you want to stay in the world of real Physics, there aint a lot you can do. You could however make the structure so larg that Gravity isnt that strong to beginn with. The Structure itself could be supported by active support such as Magnets. My suggestion Make something up. It is way more believable to say "We found new Physics X" then to have some weird explaination. [Answer] ## Negative Matter Negative matter is not the same thing as antimatter. Also, since it is not the same as antimatter, it is not expected to react catastrophically with normal matter; so, no need for fancy containment systems. Negative matter is a theoretical matter that has a negative mass, and therefore a negative gravity and inertia. By giving your civilization the ability to create Negative matter, you could fill your megastructure with homogeneously spaced negative matter plates which would create a uniform repulsion force canceling out the harmful effects of gravity and inertia inside your megastructure. While negative matter has not been proven to exist, it is easy to perform mathematical calculations on meaning that the scientific expectations of what negative matter would do if it were discovered are known and well researched. Having a predictable nature makes it a preffered subject for sci-fi writing because it means that it has the feel of a hard science while still technically being unproven. The big hurdle you will have to overcome in your audience is the preconception that negative mass automatically results in perpetual run-away motion because so many people associate negative mass so automatically with Albecurrie Warp Drives, but this is pretty easily addressed. Albecurrie Warp Drives are like magnets where you create a polar difference between two forces: positive and negative mass; however, a reduced mass megastructure would homogenize positive and negative mass; so, like a normal lump of iron, all of the forces at play would be there, just unobservable from the outside because they would cancel themselves out. The EM bonds between the regular and negative matter would be stronger than the local effects of gravity; so, as a system, the inertia of the regular matter would be stronger than the negative inneria of the negative matter; so, you'd have a stable system. Technically it would be impossible to completely homogenizing your mega structure; so, it would still be predisposed to fall ever so slightly in one direction, but this can be solved for by giving your structure a spin. Since its sum inertia and mass is so small, spinning it would be pretty easy for a system this size. So, you don't need to worry about the normal ridiculous power requirements of spinning a mega-structure. By spinning it, it might drift left a little bit as it falls one way, but then when it comes around it would drift back the exact same amount for a sum-stationary effect. [Answer] Lens. [![convex lens](https://i.stack.imgur.com/qKh7M.jpg)](https://i.stack.imgur.com/qKh7M.jpg) <http://www.funscience.in/study-zone/Physics/RefractionOfLight/FormationOfDifferentTypesOfImagesByConcaveLens.php> Consider light. It is kin to gravity in some ways. It propagates thru space and also thru different media which occupy space. It is possible to alter the course of light by having it propagate thru a different medium. It could be a different medium occupying space, like a glass lens. It could be space which is different because it is bent around a mass - [gravitational lensing](https://en.wikipedia.org/wiki/Gravitational_lens). Gravity propagates thru space and thru all media that occupy space. But like light [it is possible to bend gravity waves via gravitational lensing](https://arxiv.org/abs/1903.11809). Different regions of space can have different properties as regards the propagation of gravity and light. If it were possible to encompass a region of space with different properties once could use that space to alter gravitational effects between objects on different sides. In the image above a lens spreads out laser light. Imagine those beams of light are instead the pull of gravity from the flashlight (become a planet) and something on the other side, like a building. Refracting the pull decreases the pull. Is it possible there might be a way to alter space such that light and gravity cannot pass through it? Or are bent in such a way such that their effects do not reach the far side at all? A prism is a lens that can do that for light. Could one build a gravitational prism out of bent space? [Answer] I will accept @Trioxidane's answer as it is one that inspired this one. There were some good suggestions in comments and I think that it is worth merging them (with some additions) to make a separate answer. ## Existing theories: First of all, there is one source of antigravitation(more accurately is to call it gravitational repulsion though) that is scientifically accepted. It called "Dark energy", but the problem is that nobody knows what is this thing. There are two main theories: [Einstein's\_cosmological\_constant](https://en.wikipedia.org/wiki/Dark_energy#Einstein%27s_cosmological_constant) and [Inflationary dark energy](https://en.wikipedia.org/wiki/Dark_energy#Inflationary_dark_energy). Cosmological constant stating that dark energy is bounded to space-time so-called vacuum energy. The second theory states that dark energy is some scalar field. Secondly, it must be mention that the antimatter is sort of a hack for antigravitation because it is [unlikely](https://en.wikipedia.org/wiki/Anti-gravity#Fifth_force) to possess such properties, but it is still possible. --- ### Update about antimatter: Actually, there is a [paper](https://iopscience.iop.org/article/10.1209/0295-5075/94/20001/meta) by M. Villata(2011) with a very convincing way of describing antimatter with gravitational repulsion in a framework of General Relativity. This paper introduces antimatter with gravitational repulsion without assigning negative gravitational mass to it and addresses a topic of spin oddness of graviton. Although it received some [critics](https://link.springer.com/article/10.1007/s10509-011-0939-8) with it being [addressed](https://link.springer.com/article/10.1007/s10509-011-0940-2) later. --- ## Problems The scalar field theory is promising in terms of explanation of antigravitation. Because the scalar field may have a mediator particle, the same way as the gravitational field has [graviton](https://en.wikipedia.org/wiki/Graviton) as such. It is not very easy to come up with a way to realistically capture those as these mediator particles behave almost the same as photons in terms of interactions. On the other hand, the cosmological constant theory is more favorable from the scientific point of view but less promising for antigravitational effect explanation. If dark energy is bounded to space there is no way to extract it. ## False vacuum With this in mind let's explore one other concept: [False Vacuum](https://en.wikipedia.org/wiki/False_vacuum). The hypothesis is that there are some other states of vacuum that are meta-stable. Usually, it is used in a set up when our space-time is in the meta-stable state, and collapsing to the true vacuum may have a devastating effect on everything including matter itself. But there is another approach. Let's assume that we are in the true vacuum state, but the false vacuum state is also possible. It will require a very high energy density to reach, for example, such energy density may be unleashed when the back hole evaporates or something similar happens. [![False vacuum illustration from wikipedia](https://i.stack.imgur.com/dW4Yf.png)](https://i.stack.imgur.com/dW4Yf.png) ### Black spray The idea is that if it is reached - it is metastable and the energy barrier is high enough to provide this stability for the time that is comparable with the universe age. This state is defined only by the "volume" of space that reached such a state, the energy of this state, and the surface energy. The surface energy minimum is providing us with the spheric form of this volume. From a thermodynamic point of view if partial derivatives of these quantities w.r.t some parameters are zero it means that changing of those parameters is not resulting in force, so one can expect to be able to move this bubble of new space. Its absolute value of mass(gravitational and inertial) will be defined by the energy of the metastable state by Einstein's formula of $E = mc^2$. The energy barrier which provides metastability will prevent interaction of usual matter with the space-time of another nature preventing the need for new physics. So it will look like the "Black spray" from "Roadside Picnic" by Arkady and Boris Strugatsky. It will be almost indestructible as the energy barrier which provides metastability must be breached for the usual matter to pass-through this type of space. If it breached though, the "Black spray" will release all its energy of the $E = mc^2$ amount. ## Dark energy + False vacuum The connection between the false vacuum idea and the dark energy is that the energy of metastable space-time is needed to be stored somewhere and with cosmological constant theory in place, it will be stored as vacuum energy thus providing the stronger antigravitational effect than usual space. With the scalar field, it is a little bit trickier because there must be no other fields for the energy to be stored in dark matter's scalar field, but this just requires to be able to provide really empty space and I think it is manageable to provide a realistic mechanism to obtain such space. ## Conclusion The antigravity is provided by the dark energy that is kind of energy of the empty space(vacuum energy). If one will be able to provide a vacuum with so much energy density that part of it will reach the metastable state it will mean that the magnitude of gravitational repulsion will increase as more dark energy will appear. Metastability will provide the spatial locality of "volume" of new space and stability w.r.t external forces. ]
[Question] [ In my previous question [Would this underground city be noticed by seismologists?](https://worldbuilding.stackexchange.com/questions/183522/would-this-underground-city-be-noticed-by-seismologists), it was established that a Goblin city in one of my settings would probably not go unnoticed do to the meddling of seismologists, oil prospectors, and ground surveying projects. So, I want to see if there is anything they could intentionally do, or somewhere I could move the city too, to keep their city hidden from the humans given the following details. Sorry about the excessive setting outline, but... who they are and what they can do may have a lot to do with how they could/could not stay hidden. Beneath a major US coastal city. There is a goblin city that exists beneath it. It's chambers range from about about 500-2000ft underground and has a population of about 5-10 thousand. The layout of the city comprises of several fairly large caverns interconnected by tunnels. The largest caverns are about 30-50ft high and 200-300 hundred feet across in either direction, but most caverns are much smaller and more tunnel like. At the entrance to the city, there is a small waterfall of fresh water where the goblins dug through the water table to reach the surface. This then feeds down a bunch of streams that function kind of like an aqueduct system for the city, and ends with an underground lake that is also a portal to a pocket dimension ruled by a Sídhe Lord who uses the water to build his ever expanding kingdom of ice in the faerie world. ### What are Goblins in this setting? The goblin city is made up of goblins and their descendants who were once slaves of the Sídhe Lord on the other side of the portal who for one reason or another have gained their freedom. Returning to the faerie world or asking the Sídhe Lord for help is out of the question, as it would mean returning to a life of slavery. All goblins are able to glamour themselves to look like a human or animal of comparable size, but the glamour can be broken by direct sunlight; so, they only go out at night. To break an agreement or fail to repay a debt makes you another person's property under goblin law; so, the smartest goblins tend to rule society by getting other goblins into their debt while avoiding being indebted to others. While this law does not necessarily extend to humans, goblins disguised as humans tend to carry some odd seaming behaviours into human society like refusing to go through a door a person has opened for your or refusing offerings of free food as accepting such gifts would be seen as a debt in goblin society. These cultural differences and the limitations of glamours make long term, direct interacts with humans risky; so, goblins try to avoid it as much as they can. The goblins also do not have any proper industrial infrastructure of their own; so, a lot of what the goblins have comes from things they steal from humans at night: radios, power tools, babies, and whatever other odds and ins they find lying around. Stealing does not create a debt under goblin law since it was never offered. Thus many goblin homes are adorned much like shops with all of their possessions labeled with obscenely high price tags to make sure no one takes anything. Those pens at the bank, yes you are allowed to take them, but they cost $100 each. There are 6 distinct breeds of Goblin in the city: Grimilans: Average about 1 ft tall and have unnaturally good hearing. By disguising themselves as rodents and taking up vantage points in attics, under homes, and inside walls they tend to know about what the humans are up to giving the goblins time to react to what humans are planning. They are also known to participate in sabotage, when the humans get too close to the truth, but this is not 100% reliable since too much sabotage can create more suspicion than it alleviates. Duende: Average about 2-3 ft tall and are by far the most intelligent of the goblins. They have an average intellect somewhat higher than a human. They are too few in number to really progress goblin technology beyond that of what the humans are coming up with, but they are very quick about adapting to and understanding human technology. They rarely leave the city themselves instead preferring to use other breeds of goblins to do their bidding. Uruks: Average about 4-6 ft tall and moderately intelligent, they are the most passable for human. When goblins need to interact with the human world (while passing for an adult), it's usually a Uruk. Bugbears: Average about 6-8 ft tall and weighing in at several hundred pounds. They have temperaments and let's face it, raw strength comparable to that of a horse. Bugbears are used mostly as chattel slaves by the smaller breeds of goblins. Kobolds: Average about 3-4ft tall. These goblins have a bit more potential for magic than the other goblin races, but their magic often comes with unexpected consequences. When the price of spell is small, they tend to be able to control the equivalent exchange well, (like transmuting a silver coin into a loaf of bread), but trying to do something like hide the whole city from ever expanding human technology would almost certainly end disastrously. Red Caps: Average about 3-5ft tall. Rarely seen in the goblin city, and usually killed on sight due to their uncontrollable impulsiveness. [Answer] *Anywhere there are natural caves,* AKA IN PLAIN SIGHT: I would think that anywhere there are natural caves, geologists would see the caves, but not think twice about them. There are HUGE cave complexes around the world, and humans can tell they are there, but not do a thing about them. "Say, students, did you know the ground half a mile under the city is riddled with caves? It's true. I know some of these look repetitive and manufactured, but similar structures are seen around the world an the product of natural forces." You might have trouble with the occasional spelunker, but it's a dangerous sport, and if a magical goblin showed up looking like a fellow cave explorer and warning you this way was too dangerous, would you ignore them? If they went on, might they not meet with a terrible accident? [Answer] "The Goblin Caves are a protected scientific site of incalculable geological, paleological and anthropoligical interest. They contain the remains of an early human settlement; scientific exploration must be carried out with painstaking caution to prevent any valuable finds being destroyed. To this end, the caves have been sealed and the Committee is now in the third decade of planning its approach. "Rumors that the caves are inhabited by ghosts, aliens or goblins are of course ridiculous" "Thanks, Prof, here's the gold like we agreed" [Answer] Not really hide, but they could set up, around the city, a suitable meta-structure to diffract seismic waves around the city, instead of having them bounce off its interfaces. The same way a stealth airplane scatters radar waves away from the direction where the radar is firing them, the underground city might use a structure with proper refraction index modulation to achieve the same result. ]
[Question] [ Background for Context: For the science fiction setting I am working on, I was originally intending for spaceships of a specific faction to have solar panel arrays on their larger ships. Originally, it was more as a stylistic choice to fix up some empty spaces. Some time between designing those ships and the present, I decided I wanted that faction to have exclusive access to efficient antimatter production (where the rest of humanity use fusion reactors and vent off the plasma for thrust and certain weapons.) I got to thinking on how these solar panel arrays would be useful and decided they would be a backup power source for the electromagnetic confinement systems they store their antimatter in so that the antimattter escape if the main reactor fails. In my research, I discovered that the energy from matter-antimatter annihilation comes in the form of gamma rays which lead me down a different line of thought. Instead of just using the gamma rays to heat water to run a steam turbine like modern nuclear fission power plants, what if the faction in question had technology that could directly absorb gamma rays and convert that energy into usable electricity? That brought me back to the solar panel arrays, wondering if such tech could be applied to them as well. Question: If a passive power collection system that was both functionally and visibly similar to a solar panel could absorb gamma radiation and other short wavelength radiation in space, how much could it potentially collect before hitting any thermodynamic limits? Is there even enough energy to be found short wavelength radiation in space to justify trying to collect it as a power source? Or would it be better to leave those as dedicated solar panels and leave the short wavelength radiation-electricity conversion tech in the antimatter reactor? [Answer] It's not really a significant energy source. If you measure wattage carried by photons that pass through a particular volume of space, gamma rays are not very significant. Visible and infrared light are the wavelength where you find the most wattage. That ratio is basically the same whether you're close to a sun or not. In deep space, far from any sun, you'll get very little energy from any form of light. It's different if you're near a neutron star or active black hole which emit more energy in the short wavelengths. Though they still have more energy in x-rays than gamma rays. But, your gamma ray absorbing panels would make excellent radiation shields. One of the problems with gamma rays is that they go through everything. Gama rays don't interact with things very often, which means they will likely go through solar panels without being absorbed. If these fictional gamma panels are effective at absorbing gamma rays, then they may be more valuable as shielding than as power collection. Real world gamma ray shielding involves massive blocks of lead, concrete, water, or whatever. The only way to block gamma rays is to put enough stuff in front of it that it gets absorbed eventually. If you had a lighter, thinner mechanism to block gamma rays that might be a big deal. Especially if your ships frequent high radiation environments or if their enemies utilize gamma-ray lasers. [Answer] # It depends on the bandgap of your solar panel's semiconductor Solar panels work by absorbing a photon and using it to "boost" an electron in the silicon lattice. Once boosted, the electron is free to wander around the lattice and do work until it gives up its energy and returns to the lattice (through a process called hole-electron recombination). Thus, an electrical current is created. Photons are of course quantized, so a single photon can only eject a single electron. Einstein showed this through his explanation of the photoelectric effect. In it he found that the photon must have a minimum energy or no electron would be ejected, in other words, a photon's energy was quantized. This was actually the birth of quantum mechanics. Getting back to your gamma-ray solar panel, yes, it is feasible to engineer a panel that can absorb gamma rays, but it will not increase the number of electrons available (i.e. the current). In theory, however, it could increase the energy of the electron when it's ejected (i.e. the voltage). Since power is P = VI, you could, theoretically, increase the power by absorbing gamma rays, but it's not that simple. Modern photovoltaic cells are only about 20% efficient. Most of the photons falling on them are unable to eject an electron and are thus converted to heat. This isn't necessarily related to the photon's energy, either, it has to do with how the solar panel is engineered. So in the end, the amount of power you can generate with your solar panel is directly related to its efficiency, not the energy of the photons it absorbs. All of it falls down to what's called the "band-gap energy." This is a measure of how easy it is in your semiconductor to eject an electron, and it has direct implications on the power and voltage that your semiconductor operates at. There are multiple kinds of band gaps, but the one you care about is the optical bandgap. For pure silicon this is about 1 electron volt. For our purposes, 1eV is equal to 1V, so a single silicon wafer can generate 1 volt of electricity. The amount of electrons is going to be related to the surface area of the cell, and thus so is the current. In order to get higher voltage, you string the panels together in series. To get more current, you would string the panels together in parallel. For pure silicon, we can calculate the optimal photon wavelength required to eject an electron, and it turns out to be around 1 micrometer, which is not even in the visible spectrum; it's near-infrared! But one of the useful properties of certain semiconductors is that its bandgap energy can be changed through doping. In silicon, this is very difficult to do, but in other semiconductors such as Gallium Arsenide and Indium Phosphate, it's relatively straightforward. This band-gap engineering is how engineers control the color of LEDs. Namely, by changing the band-gap energy to be roughly the photon energy (and thus the color of the photon). For your gamma-ray semiconductor to work, you would need to engineer your solar panels to support the gamma-ray energy photons available. However, this would be in direct conflict with attempting to make your panel absorb other wavelengths, such as visible light. ]
[Question] [ Because my original question regarding the legality of DNL tech (Link here [The legality of Direct Neural Link Technology](https://worldbuilding.stackexchange.com/questions/180764/the-legality-of-direct-neural-link-technology?noredirect=1#)) was a tad bit too broad, I decided to try again, this time I will break it down into more manageable bite-sized nightmare scenarios that I think we can all agree we should all be concerned about. Now the basics of Direct Neural Link tech as previously described is all about connecting your mind to the world around you, like downloading information directly into your brain, or allowing cybernetic limbs all the feeling and vitality of good old fashion flesh and blood, or even stimulating nerves or bypassing them all together to make the lame walk and the blind see. But if you put a door in your head to let your mind out into the world, that door could also let something darker from the outside world into your skull. In this case to commit the oldest crime known to man. Cold-blooded murder. And the worst part is if we assume that DNL tech Will be half as ubiquitous in the future as depicted in most sci-fi dealing with it, there might be a variety of murders, from a jealous lover hacking the spouse of an ex to do the deed, all the up to hacking a presidential aid for targeted assassination. Now I think we can all agree that no one wants this to happen, not the populace putting this tech in their heads, not the police who would have to investigate these killings, not the muggles who like me don’t want to be in the passenger's seat when one of google self-driving cars hops the curve, runs over three peoples and drives off a bridge, and certainly not the corporations who would be sunk by the many justified class-action lawsuits. So the question is: How do we keep a psychopath with a laptop from hacking people's nervous systems in order to murder someone? [Answer] Security overdrive One way to keep your brain link secure is to hire and maintain a group of expert hackers who are constantly hacking an making fixes for possible intrusions. This is good for high profile people since this means there are team standing by for your security, and good for normal people since they get great security. The company that make this would also want this since the more people use it the more likely an attack will occur on a less important user than the people that are paying for the security service. you can also have cash rewards for potential intrusion methods so most people will turn over the intrusion method when discovered instead of trying to use it illegally. Don't trust the user In our current culture, we install apps and browse sites constantly downloading information and exposing ourselves to risk. Because of this users can easily get hacked by downloading something to compromise themselves. The solution, take away the user's freedom. you want the brand new in brain video editor, nope, you get the old, secure, tested, version that was developed in house and never updates, since updates implies security threats. Every function has one application and one application only. To browse the internet the content is scraped and scrubbed so you don't get infected and if that process can't complete the site is just blocked. Secure messaging exists, but no emojis or extra characters that could cause exploits. This isn't great, but it works. Neuroscience is hard In order to hack someone you need to first understand their brain and deal with the idiosyncrasies of its wiring. For simple stuff like putting information on the optic nerve or tapping muscle fibers that might be simple, but getting someone to alter their behavior is hard. Also, since every brain is different, every hack is different. A hack that gets the president to pass a new law will get his vice president to feel hungry and have a few memories that looks like static, and will cause a random citizen to remember static and have uncontrollable nausea. Therefore to hack a brain you need a lot of effort and at least a masters degree in neuroscience. In that case anyone who would hack a brain would instead us a cheaper solution, like a bullet or something. Limited brain functions The reason the brain is not hack-able is because the technology doesn't have the ability to to hack the brain. The link can put sensory data on nerves, interpret simple impulses to muscles, and helping you remember images and sound. But changing someone's thoughts is impossible because the link doesn't have that capability. The machine has read and write access to the brain, but your brain sanitizes inputs so you can't brain wash someone. The best you can do is send mass junk data or pain, but any person with a wrench or access to Quaalude has that ability also. you would still see jamming attacks and doing this to someone is traffic could be a death sentence, but it will mostly stop attacks. laptops are not great hacking tools Assuming that you are being literal with your laptop example, most laptops have about 16 GB of ram and a passable GPU. It is possible that to execute an attack you need to calculate information about the whole brain to manipulate every piece to get the expected result. This will probably need more than 16 gb and just ok GPU. you might be able to do hacks with Desktops that border on supercomputers, but you will keep hacking out of the true script kiddies' hands. [Answer] Take out the brain interface from the question and it ceases being a worldbuilding question to become a question more fit for security.se. With or without the brain interface, the question boils down to: > > How do we keep a psychopath with a lab top from hacking > > > Because the motive and the target are irrelevant. And the only correct answer is that you can't. Security has always been a cat-and-mouse game, and there is no indication that it will ever stop being so. So just like love and war, this is a game in which the only way to prevent a loss is by not playing it. You could live without cybernetics. It would be like living without electricity in the 21st century, which some people do on their own volition (i.e.: Amish communities). In a world that depends ever more on technology this could really get you cut off of the grid. Many good scifi stories have a plot like that, where the hero is unable or unwilling to use the latest technologies because of reasons (i.e.: the book Forever Peace, and the movie Surrogates). Otherwise, once you've got that chip in your head, you're game. [Answer] How do we prevent people from killing each other with other lethal methods we walk around with every day, like cars, power tools, or drain cleaner? Investigation and forensics. You make it likely enough to get caught that most people don't want to take the chance. Yes, it's possible to use J. Random Computer to hack J. Random Citizen's cybernetic implants in a way that kills them. However, the implants keep a hardware-level, indelible record of input received - commands, the type of equipment that transmitted them, usernames and verification codes, and the like. You could physically remove the implants, but that's just stabbing someone to death with extra steps - you'd have to be extremely careful to avoid leaving forensic evidence left and right. Otherwise, it's a matter of investigation, finding people with motive who could have sent the fatal commands, then verifying whether they have an alibi. [Answer] 1) Use Application specific chip sets (think that is the correct name) Your cybernetic system would contain a series of 'chips' specifically designed to perform one (or a specific set of tasks) fixed at the time of fabrication. Critically the programming in these chip sets cannot be changed post production (excepting perhaps in situations where the person wanting to install new software has direct physical access to the chip - in which case they could switch out the old chip for a new one loaded with the update.) So unless you 'hacker' gets you character under the knife they wont be able to override existing programs. The downside is of course that like your washing machine your character won't be able to upload or install new improved software without surgery and whatever software he does have will be relatively inflexible. 2) Limit the possibility of signal/sensor jamming or hacking by utilizing detachable external receivers if not transmitters. Links to systems inside your characters body can exist (e.g. implanted just under the skin) but the 'box' containing the receiver at least should be external and detachable. Otherwise you risk your character being attacked with hostile data inputs at critical moments or even continuously (imagine looped Celine Dion video tracks playing inside your head 24/7 with no off switch). [Answer] Am currently writing a story centered on it. I prefer to call this technology Brain Computer Interface (BCI) or brain-machine interface (BMI) rather than Direct Neural Link exactly to point out that this technology is NOT direct. You do not connect directly to the network. First of all current real [studies](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3497935/) have pointed out the difficulty of signal processing. > > Signal Processing > > One of the issues we will find when dealing with brain-data, is that the data tends to contain a lot of noise. When using EEG, for example, things like grinding of the teeth will show in the data, as well as eye-movements. This noise needs to be filtered out. > > The data can now be used for detecting actual signals. When the subject is actively generating signals , we are usually aware of the kind of signals we want to detect. One example is the P300 wave, which is a so-called event related potential that will show up when an infrequent, task-relevant stimulus is presented. This wave will show up as a large peak in your data and you might try different techniques from machine learning to detect such peaks. > > [A Beginner’s Guide to Brain-Computer Interface and Convolutional Neural Networks](https://towardsdatascience.com/a-beginners-guide-to-brain-computer-interface-and-convolutional-neural-networks-9f35bd4af948) > > > This problem becomes even more severe as you have to increase the resolution of the device to perform complex tasks. Imagine the degree of complexity going from a signal like 'go forward' to transmitting the memory of a scene you experienced. Furthermore different individuals will show different signals. The higher the resolution is the more divergent these signals are. You need an AI What is needed is a middleware resident AI (this is why the link is NOT direct) that will learn the user's patterns and will grow with him/her. A number of 'games' will be played in the learning process to align the AI. It will then be in charge of both acquiring signals from the user and act on it and receiving input from the network and activating due signals in the brain. Obviously it would also check and filter incoming data packets. Let's imagine a scenario to lay out how all of this would work. Our BCI user is sitting at a pizzeria on [Piazza Navona](https://en.wikipedia.org/wiki/Piazza_Navona). Being an English speaker she forms the thought of "how to order a Pepperoni Pizza in Italian". The signals of that thought are read by the resident AI that has been trained for years in reading correctly her thoughts. The AI then prepares the inquiry for the network and provides a crypto code attached to it. The inquiry is posted to the network servers through secure protocols. These servers are registered and certified so that they can provide the results of the inquiry with a corresponding crypto code. The AI receives the packets of the search results, verifies that the provided crypto codes match, scans the packets for malicious instructions. Then examines the results. If needed performs further research to refine the results. All of this in a matter of milliseconds, without disturbing the user. As the results satisfy the AI it presents the answer to the user such as: "posso avere una pizza ai peperoni per favore?" but also with the notion that there is not such a thing in Italy. So, a malicious attacker would have to find a way through all of the security in place and fool the AI into forming signals with malicious consequences. No system is 100% safe, but chances of success in an attack would be lower and lower the more complex the information passed on is. It would be impossible to bypass the security to control someone as a remote tool but it may be possible to manage implanting in his / her mind ideas through careful feeding of information. But does not that happen all the time with us? Would the user be able to detect an external thought inserted in her mind? Would it glaringly show itself? "Until yesterday I was happy with Norman but now I have this feeling that he is up to something". Well, it's your story, up to you to decide. ]
[Question] [ ## Ocean sourced Trade goods in a Renaissance era Earth I am in the process of writing a fantasy book that is set in a post-apocalyptic late medieval/renaissance era society. This is on Earth, about 1300-1500 years in the future following a complete societal collapse of decades. A group of aquatic humanoids (I call them Delphians,) need to trade for metalwork goods, and I'm having difficulty finding trade goods that would be valuable to the land-dwellers that would be found in the ocean, other than seafood. I've come across a few of them in my research that are available in today's society (regardless of legality or morality), such as: 1. whale ivory 2. mineral or metal nodules 3. leather 4. pearls (rarely, very druidic/harmonistic society underwater) and possibly 5. sea snails for the old fashioned purple dye Thus far in the build, the aquatic humans are the only unusual biological presence other than a semi-intelligent parasite. My question is, What sort of resources valuable to a Renaissance era society would come from the Continental shelf of the ocean? Especially if it would be different from what is available or valuable in our modern era. [Answer] *Service:* These are great answers, and materially I can't compete with them. I see potential in labor as a marketable trade commodity. Humans have a long, complex relationship with the sea, and the labor of those who can move freely in it could be very valuable. My commercial ship sank? Hire a mer-crew to retrieve the goods. Want cold wine? I know a mer-guy with a deep hole where it gets cold. What ocean voyage is safe without a mer-guide to escort you and smooth over potentially hostile relations? An angry mer-tribe will come and drill a hole in your ship if you tick them off, but with a guide to vouch for you, and possibly lubricate trade, your voyage becomes successful. They also know where the sandbars and clear channels are, and probably have ways of navigating the poor humans have no chance of competing with. Navigators were highly sought-after, but perhaps merfolk are SO good at it that no one uses them. On the less scrupulous side of things, merfolk could be excellent mercenaries on the sea. What pirate wouldn't give all the crappy metal loot to merfolk in exchange for their help sacking ships? Jam the rudder on a merchant ship and good luck outdistancing pursuit. Alternately, jam the rudder of a pirate ship so the merchants can escape. This could even be a semi-acceptable protection racket. Well, haven't you noticed how bad the pirates are? I promise you will have no problems crossing this trade route for a modest fee. [Answer] Valuable dyes. In particular I am thinking of Tyrian purple sometimes called Phoenician purple. This was a dye made from a particular sort of sea snail. They were gathered, mashed up, and the concoction was supposed to be the most foul-smelling thing imaginable in the ancient world (which is saying something, they weren't necessarily known for their hygiene). After fermenting for some set period of time, it could dye cloth a color that was impossible otherwise until the advent of aniline/synthetic dyes. What that color is, exactly, is unknown... I don't believe any examples survive. Now, that doesn't mean that it's just "purple dye", or even "just a dye". Any number of strange biological substances could come from a sea. Pharmaceuticals (abortificients for instance) were difficult to come by, and could have almost any property that modern pharmaceuticals have. Nearly anything that served the needs of your story could be chosen. The only restrictions would be (if details were necessary) to tie it to an organism that lives in fairly shallow water (no more than about 40 meters deep), as they'd have trouble collecting it otherwise (fish can be caught at deeper depths, but are less plausible as the origin of interesting substances). [edit] Didn't realize this question referred specifically to mermen. I retract the "shallow water" constraint. They can go just about anywhere to get the stuff, which may open up possibilities. [Answer] Relics of the sunken world. [![enter image description here](https://i.stack.imgur.com/rGfyc.jpg)](https://i.stack.imgur.com/rGfyc.jpg) <https://www.youtube.com/watch?v=YCQ6ADnxStI> The screenshot is from the movie Waterworld, where the merperson hero can visit the sunken cities and retrieve items. Mostly dirt, if I recall. But in your post apocalyptic world, maybe the merpeople have access to sunken relics of the world that was. Their remoteness means they escaped looting in the centuries since the apocalypse and their deep locations means that the loot as escaped the travails of surface wind and weather. The merpeople often do not know the significance or value of what they retrieve. [Answer] Ambergris is used to create perfumes and is a very expensive commodity mainly because of its elusiveness. It is formed in the bowels of whales, perhaps they have discovered a way to farm whales for this resource? <https://en.wikipedia.org/wiki/Ambergris> ]
[Question] [ It seems to be a really common trope in futuristic movies to have visible force fields, but based on a [couple](https://worldbuilding.stackexchange.com/questions/113058/somewhat-realistic-force-field) [questions](https://worldbuilding.stackexchange.com/questions/176655/how-would-a-real-life-force-field-work), it seems like it's not all too realistic to create a small force field (size of a doorway) due to the amount of energy taken. However, I was hoping to take a different look at this concept. In the Avengers series, we see Wakanda sporting a large-scale, but not as powerful force field surrounding the entire city. At first glance, this seems largely impossible due to the amount of energy required to create a small field, but I think the metrics could be somewhat changed in this scenario. During the battle in Wakanda, it seems like the power of the force fields is somewhat weaker than the average force field, as there appear to be Outriders (bear-sized dogs?) that can push through the force field with enough power. Additionally, assuming that Wakanda's vibranium supply could be replaced with a realistic nuclear power plant, it seems like it would be within the realm of possibility. One minor detail seen in the film, as well, is that there seem to be divisions of force fields, where some sectors can specifically be unlocked. This could lead to a theory that there are invisible force field emitters bordering each of these sectors, if that happens to help. I'm wondering if it's possible to create the kind of force fields seen in this film, and if it's not possible, what relative scale would be more feasible (size of a small house, size of a person, etc.). As far as requirements for the field: * I was hoping for it specifically to be mostly translucent (color doesn't matter, but should not be completely invisible or completely opaque). * Field should produce electrical energy that's applied to a person on contact (doesn't have to be electrical arcs) rather than just proximity. * As for strength, I'm fine with it being relatively weak, but it should somewhat hinder small-arms fire/organic creatures from passing through. Not particularly sure if this fits the `hard-science` tag, so I'm leaving it as `science-based`. Thanks for reading, y'all! [Answer] Visible shields are not a well thought out trope. Unless you are using it to stop a persistent and ever present threat like radiation, it makes a lot more sense to make them reactive, not preventative. What I mean by this is that you would only project it where you need it for a few milliseconds, and then turn it off when the threat is past. By doing this you can multiply the shield's power efficiency by many orders of magnitude which makes passive shielding a pretty bad tech to invest in. Just to put this in perspective, a basic shield window takes 8 kW/cm^2; so to passively shield a city that is 10km across you would need about 150,000 gigawatts. Even if you were to fill the entire landmass of the dome with a giant nuclear power plant and all of the supporting infrastructure that a nuclear power-plant needs, you would only produce about 26 gigawatts of power. This is not nearly enough to keep the shield up continuously. Now if your goal is to stop a hoard of Outriders, it turns out you don't really need a full shield dome sense a shield fence would probably suffice, Outriders don't really seem to be able to vertically jump more than 1 or 2 meters, so a 4m wall would probably be all you need to stop them. A 4m perimeter shield around a 10km city would be only be about 126,000 m^2 which would only take about 10 gigawatts of powery. While far from practical, this atleast becomes doable. That said, a visible full dome shield may be achievable anyway if you change your thinking a bit. What you could actually have is a physical dome made out of plasma windows. In this case you would have a "shield dome" over the city that is always there with or without power, and when a threat comes in, the needed window turns on to intercept it. In this case the city has an ever present shield dome without wasting 5 times the collective energy budget of the world to fuel it. This would work great with your Outrider invasion because if the whole city were put under siege where you needed to turn on a persistent ground level fence, it would pull those 10 gigawatts just to get a basic 8 kW/cm^2 shield window to hold the enemy at bay. Such a fence would burn like hell to run through, but probably not have enough repulsion to stop a moving body. But, if instead your city were to come under artillery bombardment, it could activate just a few windows at a time pouring those 10 gigawatts into highly concentrated plasma windows that could offer thousands of atmospheres worth of resistance just when and where they are needed both vaporizing and repealing just about any form of matter or energy you can think to bombard it with. One final note: Plasma windows that are strong enough to repel physical matter are VERY bright. Basically picture a fire, then picture a fire that burns so intensely that it would physically push you back if you get too close. Now picture what would happen to your eyes if you were to look at such a fire... So, to make a science based shield that does not do more harm than good, you'd need to use a "dark plasma shield". There is some research to suggest there are methods for making plasma shields darker, but none have proven effective enough yet to safely and significantly interfere with ballistic weapons. [Answer] ## Use Utility Fogs for Force Fields [![enter image description here](https://i.stack.imgur.com/Pa7e2.jpg)](https://i.stack.imgur.com/Pa7e2.jpg) There's a significantly cheaper way to do traditional sci-fi shields around stationary targets using [utility fogs](https://worldbuilding.stackexchange.com/questions/169043/sanity-check-utility-fog). A utility fog, despite the name, is not a gas at all. Instead, it is a solid metallic mesh of 50 millimeter scale robots that move by holding one-another using small extending "arms" that can reach up to 50 mm from the center of the machine and end in "hands" that can grasp the next micromachine. These machines arrange themselves as a network, structurally supporting one another and giving strength to whatever overall form the network takes. Because of this ability to modify their overall structure on-demand, they can assume a wide range of shapes, thicknesses, and mesh densities (# of machines per cubic meter). Although frequently imagined as an always-moving dynamic mesh, a utility fog could enter a rest state where it retains all of it's strength (roughly 800 kpsi for a utility fog made of aluminum). [![enter image description here](https://i.stack.imgur.com/QhUBe.jpg)](https://i.stack.imgur.com/QhUBe.jpg) Because it is pretty spread apart, the material is mostly transparently optically. The computing part of each node is about the size of a grain of pollen, so the overall optical effect of a utility fog shield would be a hazy day due to high pollen count. Additionally, the mesh could be plated with a nano-material that is functionally the opposite of [Vantablack](https://en.wikipedia.org/wiki/Vantablack). That is, instead of absorbing energy, it could have an extremely high index of refraction to certain frequencies; greatly diffusing that radiation. As an active material, utility fog could have many of the traditional sci-fi shield effects : * it can "brought up" and "taken down". * they could emit a small amount of light while operating to let people know where the barrier is. * The material can be "reinforced" by either drawing from a reservoir of unused micromachine "grey goo" and thickening or increasing the density of parts. * Holes broken through the material can be healed. * Power can be drawn from some facility that the utility fog mesh is electrically connected to. As seen in some shows, utility fog shields could also be used offensively. With safeties removed, the shields could crush, slice, electrically shock, or merely restrain personnel and vehicles within the field. [Answer] Molecularly Aligned Air I'm going to take some inspiration from L. Ron Hubbard's [Battlefield Earth](https://en.wikipedia.org/wiki/Battlefield_Earth_(novel)). In that novel, the Psychlos had developed galaxy-spanning but very practical technology. And like any good author, Hubbard spent just enough time on the scientific theory to whet the reader's appetite, but never so much that it compromised telling a good story. Like the Psychlo force fields. Great cables were laid underground, surrounding the cities and facilities of the Psychlos. The cables caused the air above the cables to align such that nothing could push through. Bits and pieces of trees, material blown on the wind, even birds would get stuck on the surface such that, when shut down, the debris would fall to the ground. You could easily imagine something like creating a form of glass — made of crystalline air — and we would perceive it in a similar manner. We're used to seeing gaseous air, so the static air would look odd. Indeed, as light hits it at the right angle (just as it does with glass), it would shine and reflect. But what about the science, and can we estimate some power requirements? I can't... but there is this: DISCLAIMER: This is NOT my field of science. I haven't but the vaguest idea if what I'm about to discuss is applicable or appropriate. But it's fun to imagine.... Based on an excerpt from [Advances in Nonlinear Optics](https://books.google.com/books?id=mCd1BgAAQBAJ&pg=PA215&lpg=PA215&dq=can+we+align+air+molecules&source=bl&ots=B_kS0w9woC&sig=ACfU3U05JNN5aEEMR6Y7rtdywW9yhLPURg&hl=en&sa=X&ved=2ahUKEwi_-KHNr-fpAhVrFTQIHT1QCWYQ6AEwAHoECAgQAQ#v=onepage&q=can%20we%20align%20air%20molecules&f=false) it appears it's possible to align air molecules creating, at least, ions if not plasma (I think there's plasma... it doesn't help that Google won't let me see the pages before or after the excerpt. Is it junk science if you can only read a couple of paragraphs? Probably. I don't exactly know how the lasers are being used... but it sounds fun! Cheers!) So, the idea of aligning air molecules exists. Can you align them with enough density to reject something getting through the screen? We can't do it, so we can't prove it, but why not? Think of it like weaving threads to create a trampoline. An impacting object might even be thrown back as the aligned air molecules reassert their dominance and snap back into place. And whether that article is talking about ionizing the air or creating or using plasma to create the alignment — the result is that you have a strong electrical charge coursing through the screen. * What this idea doesn't do is create a curved screen. That's actually a harder sell for me in science fiction. Magnetism could arc over the top of a city, but without emitters at the perimeter and a receptor above the city at the center (or vice versa), I personally don't buy the idea of covering the city. At this time, I think that's still in the technobabble stage of the scifi-to-science transition. * I do think that needing massive nuclear reactors is near-sighted. We're looking at power generation from today's perspective, not tomorrow's. I'm a fan of Isaac Asimov's [Foundation](https://en.wikipedia.org/wiki/Foundation_series) series of novels where he presents the idea of miniaturized nuclear reactors small enough to wear as jewelry. So, if you're going to imagine the plausibility of an actual city-sized shield, it should be an axiom that improving the size-to-output ratio for energy generation is possible. * As for divisions. Anywhere you break Hubbard's cable such that it can be activated independently from the rest, you have your segment. * Finally, it's worth noting that Hubbard's brilliance came out in the details. The obvious weakness of any shield generator are the emitters/receptors. On a space ship they're inside the shield (like a fountain pump is below the plume of water). But that's more problematic for a city — and Hubbard came up with something practical and therefore suspension-of-disbelief plausible. So, obviously, to protect them, he buried the emitters. ]
[Question] [ I'm working on some biologically realistic interpretations of fantasy creatures, such as Orcs and Ogres. They're signature superhuman strength has been given a scientifically realistic reasoning to it: Their muscle twitch fibres are more fast-twitch than that of a human, whose muscles have mor slow-twitch For context, muscle-twitch fibres are categorized into two types: The high-power fast-twitch and the high-endurance slow-twitch. Many species, including most primates, feature more fast-twitch muscles than slow-twitch muscles. They have a higher power output but lower endurance compared to humans, whose muscles are around an entire 50% comprised of slow-twitch muscles (give or take 10% or so). The biggest benefit of having slow-twitch muscle fibres is a lower energy cost, which in turn can have excess energy stored as either fat or used to fuel the brain (At least, this is my understanding) However, could a humanoid species with more fast-twitch muscle fibres (like say, comparable to that of a chimpanzee or a gorilla) still maintain something close enough to human-level intelligence? Fast-twitch muscle fibres, due to being higher power, take up more energy, hence their lower endurance. This would leave less room for fat reserves, and more importantly brain fuel. Is there any special setup that could be used so that a humanoid creature can have both fast-twitch muscle fibres AND human level intellect? I already can imagine compromises such as a higher caloric intake, less endurance, and less capacity to build fat, but would this all truly work? What else would need to change in order for a humanoid species to have intellect comparable to a human? (When I say "comparable", I mean in terms of comprehension, versatility, vocabulary, adaptability, intellectual capacity, and strategizing. I imagine the traits of their brains might need to be changed too.) [Answer] There's no contradiction It's true that 'fast-twitch' muscles are more powerful than 'slow twitch'. However, what isn't true is that the primary advantage is based off of slow twitch taking more power - it actually doesn't! Since slow twitch muscles are endurance muscles, in the short term, fast twitch will eclipse them, however, long term the slow twitch endurance muscles will burn more energy. Humans are creatures designed for endurance, not power. Additionally, it doesn't matter how strong the muscles are or how much energy they take in. There's not a hard limit to how much energy a human, or any creature, can take in and use - as long as they have the systems and facilities to it, they can use it. Saying creatures spend more energy on muscles and therefore can't be as smart is like saying professional athletes can't be intelligent because they have too many muscles. [Answer] The brain is plastic, it adapts... When an athlete gains muscle mass some stem cells on the back of the head are used to create new brain cells, and when animals become bigger with more muscle their brains grow too. ]
[Question] [ Im writing a story about a boy in the year 2033 that is immune to a zombie like virus (world war z like zombies) and when he is bitten instead of turning into a brain dead zombie/infected his body is able to co-exist with the virus without killing him. He ends up gaining super strength and speed. This virus quickly mutates the body for different tasks (ex. an infected with a bullet proof head, one that spits stomach acid or keratin like armor ) is their a way to implement increased strength without changing muscle size like cartilage reinforcing muscle tissue or bones being unbreakable? He also has an ability which lets him use a certain mutation from an infected hes eaten is this probable? he also ends up developing heightened vision and hearing. i know the formatting is weird and hard to understand but im sleep deprived and running solely on coffee so give me a break if you have any questions feel free to ask and ill answer em' [Answer] One way to achieve some increased strength would be for the virus to totally override the bodies own natural neurological stop points for muscle movements and the pain threshold. Doing this would provide a significant amount of extra strength at the risk of causing some damage in extreme cases. It might also be possible for a virus to interfere with the number and type of muscle cells providing additional strength. For example by increasing levels anabolic steroids and a range of other hormones. It might also alter gene expression and even introduce genes of it's own. Bullet proof heads are a very tall order as would be keratin armour. But spitting stomach acid might be achieved by over stimulation of some body systems triggering involuntary projectile vomiting to specific stimuli. [Answer] Viruses can do many kinds of stuff to the body. For example, the one that causes COVID-19 can cause shut down your senses of taste and smell (I don't know if it's permanent though). Ebola can temporarily change the color of your eyes. And as far as I know genetic therapy uses modified viruses to deliver new genes to specific cells, in order to get them working properly. An artificial virus could deliver genes to the gonads and adrenal glands, causing them to produce more testosterone. The infected would bulk up in a matter of days (provided they exercise). [Answer] I'm not sure if symbiosis from a true mutualistic perspective with a virus is possible, as viruses are natural intracelular parasites, but other than that it's not that bad. Your pathogen seems to be closer to a bacteria, and one capable of editing human DNA. Regarding the changes in the body. Enhanced vision and hearing can be achieved mostly by a higher number of cells responsible for these activities. Considering we have birds with smaller eyes but higher cone density, it's not impossible. Considering the muscles, you could maybe increase muscle density and reduce a little the layer of fat, but a significant increase will need additional muscle mass. To make that addition as small as possible, your pathogen could be modifying the bones' internal structure to strengthen them (maybe remaking links or incorporating particles to strengthen it, though it can't be truly unbreakable, that's impossible), as well as reducing some of the natural limiters your body imposes to your muscles (we're actually much stronger than what one usually sees, but it's precisely because using such strength is both tiring and potentially harmful that our brains limit it. There are several cases of people with tetanus breaking their own bones during the violent muscular contractions the disease is known for, and your mandibles on a daily basis can bite a finger off). Regarding the mutations from the eaten zombie, I don't think so, at least not by eating. You said that the pathogen can force the body to develop different adaptations, but for that the pathogen needs information. Digesting the mutant will break down his precious genome and with it, it's ability. If instead of eating your character absorbs a part of it, we could have something similar to what happens in bacteria, with one sharing a beneficial mutation with others through the use of plasmids, except in here the plasmid would be a bit of the other zombie's body, whose genome is analyzed and broken down so the pathogen gets the info it needs to apply the mutation to the boy's body. So, can the scenario you want happen? By going 100% into the real world logic? "No". It's not that it's truly impossible, but it wouldn't be like you described, and would take much longer periods to happen. However, taking science in a bit looser way and with a tad of sci-fi logic, yeah everything you want to implement is more or less doable, given it has in ways real-life examples (although usually on a smaller scale and taking more time to happen). [Answer] Your boy is vat grown from engineered stem cells In the future, need for replacement organs gives rise to factories for such. Stem cells capable of differentiating into organs are grown into a basic human framework capable of supporting the organ until harvest. Usually, mechanical and chemical methods are used to "prune" the host organism, preventing growth of arms, legs, brains and the like, and devoting resources to growing the desired organ. There is a breakdown in a factory of this sort and the pruning ends. Many of the vat grown organ hosts die, but one lives and grows the body that his genetic code tells him to have. This is your character. He has a good brain but he does not know anything. He pretty much is operating on instinct initially. He learns fast. His stem cells are superfluid and this accounts for their flexibility. Stem cells of his type are actually used for other commercial applications - for example migrating into and augmenting muscle in athletes or person who have been injured. Once he learns how to use the programming app, he can reprogram his cells. Increased strength does not happen in 5 minutes; it takes days, lots of food and exercise. But he can go from spindly vat twerp to muscleman in a few weeks once his cells are set to work. As regards zombie bites his cells have accelerated apoptosis. Any detrimental change and they die are are replaced. This is necessary because they are prone to malignant transformation and taking over the vat. His body cordons off the infection fast. Transformed or infected cells just die and slough, rapidly. He can heal, but new stem cells have to show up from elsewhere and built tissue - it is not in seconds like Wolverine but over a few days or weeks. ]
[Question] [ We divide the year into months of ~30 days because that’s roughly the period of the moon, adapted to fit a solar year. However, would a civilization living on a world with no moon but a year of ~365 days with seasons and a day/night cycle still come up with a ~30 day month? I understand that there are benefits to the creation of months, even in non lunar/lunisolar calendar such as in the Gregorian/Julian calendars. They allow for the division of the year in everyday usage (it’s easier to say June 23, 2020 than 175th day of 2020) and schools/businesses can divide the year into quarters. However, these were created with the Moon’s period in mind as a modification of previous lunar/lunisolar calendars. So would a civilization living without a Moon still come up with months? Would they still be ~30 days or would they be based off of something else? I was thinking about maybe using solar constellations or other stars to divide the year, but they’re not as noticeable as the moon. So would they? To confirm: these people have 10 fingers and ten toes and are humanoid [Answer] You mentioned seasons, so it is most likely that your planet has an axial tilt. That means the lengths of daylight would change throughout the year. This makes four points in the calendar - the equinoxes. I suspect these would become a natural division of the year into quarters. So instead of 12 months, the year would be divided up into four quarters, and they would be named much like our seasons - winter, spring, summer, fall, based on the typical weather patterns and temperature of each. Or they could be named based on the lengthening and shortening days - daylight increasing, daylight maximum, daylight decreasing, daylight minimum. That gives 91 days per quarter, with one day left over. Universal holiday for New Years' day turnover, maybe? I also suspect that, humans being humans, and our bodies tending to a seven-day weekly work cycle naturally, there would be weeks of, say 9 days, 10 weeks, and again one day for holidays each quarter (Hoorah!!! Everybody loves holiday celebrations.) Like Australia, I would suspect periodic payments (rent, utilities, mortgage) would be divided by these 'weeks', and not by the quarters. (In Australia, rent is paid by the week, so as to not have one rent payment for 29 days, another covering a 31 day period - simplifies things like interest, for instance). [Answer] Probably not exactly 30 days, but there's another constant that might help you out here. The number 10, which is a staple throughout cultures and periods. The reason for this, from my understanding, is because we have 10 fingers. For the uneducated, which meant the majority of the population for the majority of human history, the limits to which they can count is given by their digits, plus two for each hand or foot or whatever they used for the last two. This is why we write numbers in the decimal system today. This is (probably) why numbers, at least in English, have individual names up to twelve, then follow distinct mathematical patterns. Going further, a common unit was "the dozen" because that's what a normal person could verify. Then you could have "two dozen" because you were able to verify one, then the next and so on. Apparently, even the reason we have 24 hour days is somewhat related to the number 10. <https://www.abc.net.au/science/articles/2011/11/15/3364432.htm> So, looping back to the concept of months, your civilization could just decide to divide the year by 10, leaving you with 5 36-day months and 5 37-day months. Or, you go back to the number 12, which is conveniently how many months a normal year has, and divide it thereby, because everyone can count to twelve. [Answer] The short answer: it depends. The long answer: Our moon has a very intresting rotation and syncronization with the earth and the moon.Our moon just happens to have some very intresting connections to 12(that may have something to do with our existence as a whole), too many that i would need to go into enough detail that i would be bored. Basically, if there is no moon, there is little to no rotation of the planet in question, so all potential systems of time measurement would have to be based upon the star it orbits. From there, it all just depends on how close the planet is to the star, how much it rotates and tilts(seasons would be very complex), the movement of bodies in the system, and so many things that it would be impractical to talk about in one post. Basically, their is little to no chance that the system of time would be close to or even resemble our system of time-days, months, and years would have to be changed and suited to the planet. Note: a intresting question to ask would be would there be eclipses? [Answer] it actually was the Romans who invented the concept of month. (two of the twelve months are directly named after Roman emperors: august and July. Julius and Augustus Ceaser) so most planets would have no concept of months, and from what we know of exoplanets, the length of a world's year varies dramatically, as does the day length, which in some case is the year. so in most cases the concept of months and weeks would all likelihood only exist here. Of course they would have their own measure of time, but i can guarantee it'll be nothing like what is seen here. like Trappist 1e, that planet has a year length of six days, and would never have seasons. but I'm playing a very big guessing game, and we humans have the bad habit of applying our own qualities upon something that has none of them, nor would care. We see this a lot in movies, which is why I don't watch them. most movies, albeit watchable, tends to be very misleading in a big way to those watching them. [Answer] They certainly would not invent the "month" per se, as it would be a meaningless concept to them. But that doesn't mean that they couldn't invent any unit of time shorter than a year. As @JustinthymeTheSecond points out, another obvious unit of time for them would be the season. And they might well invent some other arbitrary but convenient unit of time. There's nothing particularly natural and obvious about dividing the day into 24 hours. But people nevertheless invented the hour because day was too long a period for many purposes. Likewise there's nothing in nature that corresponds to a decade or a century, but people invented those units because counting in just years got awkward. Etc. [Answer] At minimum a division of the calendar at the soltices and equinoxes would seem inevitable for their utility, whether those count as 'months' though is debatable. But some cultures divide the year into five or six seasons, incorporating monsoon cycles and other phenomena, so even what constitutes a season is somewhat subjective. It also ought to be mentioned that the 12 month calendar's connection to the moon is somewhat tenuous. The moon does 13, not 12, complete orbits every 364 days, only aligning with the solar calendar once every 33 years. As with our calendars, your moonless Earth would likely subdivide the year for practical and cultural purposes, and like us the calendar would evolve to incorporate changes for political reasons. The rationale for those divisions and the final shape they take would be as arbitrary as our own. ]
[Question] [ After looking at concept art of various humanoid creatures portrayed in science fiction I noticed many artists tend to make the abdominal muscles of their creatures/aliens look similar to those muscles found in humans and other primates. I would like to know if a non-primate mammal/reptile/bird does become humanoid (perhaps through the process of convergent evolution) how different would their abdominal muscles realistically look like compared to those of primates? [![enter image description here](https://i.stack.imgur.com/ZQ7Mo.jpg)](https://i.stack.imgur.com/ZQ7Mo.jpg) [Answer] Not a lot different, really. Well, as it turns out, with evolution being what it is, animals being descended from earlier kinds of animal; it should come as no surprise that the anatomy is going to be relatively familiar across species. The images shown here demonstrate that even between amphibians and mammals, there's quite a lot of similarity --- the musculature comprises homologous structures. You can clearly see the pectorals, rectus abdomini (six/eight pack), the external obliques. As for the motivations of fantasy artists, I've noticed that, anatomically speaking, when it comes to werefolk of one kind or another, artists tend to plop a cat or dog head onto a human body, cover it with fur, give it an anatomically incorrect tail and call it a day. They don't make tiger people's bodies look very tigerlike! I think the reasons for this are twofold: first, trying to figure out what a feline body will look like after millions of years of evolution into an upright posture is no easy task. Bones will lengthen and change shape; joints will move differently; muscles will alter their place and function. The resulting body might look something like a human body -- maybe thinner and more flexible -- but its shape will be quite different even though the underlying muscles will all have human homologues. The second reason is boobs. Yep. Whenever we see a Werecat or Werewolf or Werewhatever female character in fantasy, what do we see? Wide human hips and big human boobs high up on the chest. If you've ever owned a girl cat or dog, you know that wide hips and high boobs are not a thing among most animals. I suspect that a real Werecat would retain a relatively narrow pelvic girdle and six or eight tits along the abdomen. Not very sexy for movies, but, that's reality check! Here's a cat: [![enter image description here](https://i.stack.imgur.com/SmAXS.png)](https://i.stack.imgur.com/SmAXS.png) Here's a dog: [![enter image description here](https://i.stack.imgur.com/DdcpA.jpg)](https://i.stack.imgur.com/DdcpA.jpg) Here's a frog: [![enter image description here](https://i.stack.imgur.com/Zomiy.png)](https://i.stack.imgur.com/Zomiy.png) [Answer] ## Only if it is a mammal. if it is mammal not much will be different, mammals are pretty conservative in their anatomy. frogs have a similar muscle pattern, frogs are really specialized and derived and have lost a lot of bones(this is also why they should not be used for high school dissections, they are misleading). but Basically all other vertebrates have ribs all the way down, the major exceptions being crocodiles (which have gastralia so still no six pack) and frogs which can have six packs and a few squmates which have a lumbar region too but it is pretty rare. If they are crocodiles, birds, dinosaurs or any of the archosaurs, it is impossible. These groups have gastralia which is an extra set of ribs in the belly. A therapod for instance will not have a six pack the closest it could get would be a 40 pack thanks to all the gastralia. dinosaurs [![enter image description here](https://i.stack.imgur.com/sSGlB.png)](https://i.stack.imgur.com/sSGlB.png) Crocodiles [![enter image description here](https://i.stack.imgur.com/AiD0i.png)](https://i.stack.imgur.com/AiD0i.png) birds [![enter image description here](https://i.stack.imgur.com/yRQXI.png)](https://i.stack.imgur.com/yRQXI.png) [Source](https://www.researchgate.net/figure/The-position-and-general-morphology-of-the-gastralia-in-Theropoda-A-subadult_fig1_40662912) there are plenty of other complications as well, in birds for instance the wing muscles cover the entire stomach reaching the pelvis even, and you have things like turtles with shells. ]
[Question] [ So, I was wondering if for small scale weaponry (150mm guns and smaller) using a coilgun to assist in the acceleration of a traditional chemically accelerated round, either while in the barrel burning the propellant, or after the round has exited the length of barrel required to burn the propellant. [Answer] It could be used to supplement the speed of a chemically propelled weapon but unless you like the flavor of a hybrid launcher it's probably impractical compared to a strict magnetic or strict chemical system. The kinetic energy of a projectile is proportional to the square of the velocity. If you have maxed out the energy that you can add to a projectile via a chemical propellant to get a 50% increase in the velocity you'd need to put in more than double the energy. Unless you absolutely need the extra velocity, you're adding an entire extra system that needs to be powered, maintained, and carried for a nebulous benefit. If modern firearms are any indication getting a minor increase in velocity isn't going to be worth it. [Answer] In principle, you could, however there are going to be a number of practical considerations. For the lengths of the weapon you stated, (~150mm- I'm going to assume this is the total length as opposed to barrel length) you wont have a significant amount of space to fit your coils, and on top of that you are going to need to keep your power source. Considering that the amount of energy you can impart to the projectile through EM fields is related to the length of the barrel, you would likely not gain any substantial increase in muzzle velocity. If it did work at all, you would get a small increase in velocity at the expense of a substantially heavier and larger weapon, when you in all likelihood could have achieved the same effect by user 'hotter' ammunition. [Answer] Frictionless barrel + afterburner oomph <https://en.wikipedia.org/wiki/Coilgun#Non-ferromagnetic_projectiles> > > Though the cost of power switching and other factors can limit > projectile energy, a notable benefit of some coilgun designs over > simpler railguns is avoiding an intrinsic velocity limit from > hypervelocity physical contact and erosion. By having the projectile > pulled towards or levitated within the center of the coils as it is > accelerated, no physical friction with the walls of the bore occurs > > > Physical contact and friction is an issue with chemical firearms too though arguably less than with a railgun. I could imagine a hybrid setup with a snubnose pistol type chemical firearm. This accelerates the projectile into the coilgun which accelerates it further. Acceleration conferred by any firearm is proportional to the barrel length. The cool thing about a coil gun is that regardless of how fast the bullet is moving when it enters, the coilgun can accelerate it faster. > > A superconducting coilgun called a quench gun could be created by > successively quenching a line of adjacent coaxial superconducting > coils forming a gun barrel, generating a wave of magnetic field > gradient traveling at any desired speed. > > > Good old 1/2mv^2. The wallop packed will increase as the square of the added velocity. Of note - a coilgun that worked like an induction brake need only induce a current within the projectile to make it into an electromagnet. Your bullet does not need to be a magnet itself. The big question - it is possible to impart spin on a projectile as it travels in a vacuum thru a coil? ]
[Question] [ It is an undisputed fact among scientists that individuals, groups, and peoples are subject to the same Darwinian laws of natural selection as plants and animals. Social Darwinism has proven that the strongest among us survive, and the weak must suffer what they will. I, a magecraft sorcerer, now have a legitimate policy to justify my imperialist actions. To accomplish this, I steal the lives of individuals by sucking out their souls and consuming them into myself. There, they will suffer excruciating torture for an eternity while I realize my noble ambitions of manifest destiny. The suffering of countless innocent men, women, and children being robbed of their lives as I steal their souls provides for the most exquisite torment. It also extends my life and provides fuel for my sorcery. As a result, I have managed to extend my life for many centuries, robbing the innocent of their worthless lives while making myself more powerful. However, The hundreds of thousands of souls yelling and screaming all at once is at risk of driving me insane. Hearing so many voices can make me lose sense of self, leading to schizophrenia. I may also confuse one of those soul-personalities for my own. This constant puts my self-identity at risk. I need to continue absorbing souls to extend my unnatural life, but at the same time prevent them from taking me over or causing damage to my own mind. How can I accomplish this? [Answer] Actually, it's better if you don't Aren't you contradicting yourself if you do? If you truly believed in Social Darwinism, and that the strong deserve to lord themselves over the weak, and that the weak deserve to suffer, than you should also believe that you're inherently superior to all those souls that you've eaten inside you. See, if the soul stealer really is the big cheese, then he has nothing to fear from all those weak-willed souls running around inside his body because he is strong and they are weak. Furthermore, if one of the souls manages to steal the body from him, that means that that soul deserves to be in control and the soul-stealer deserves to suffer - because, after all, Social Darwinism, strong eat the weak, weak suffer, you get the point. Only a weak and feeble soul eater who doesn't believe in their own natural and inherit superiority over the feeble scrubs that they're eating for souls would choose the coward's way out and decline to allow the souls a futile and inevitably meaningless attempt to overwhelm them with their pitiful cries of pain. If you do feel sorry for them, of course, it just means that you're not cut out for the job. [Answer] 'Insanity' is a broad but you seem to be talking about schizophrenia specifically I would argue that there are many outcomes of a person experiencing constant screaming in their head, all of which fit into some definition of psychological abnormality: * A complete lack of empathy: Once your sorcerer has managed to get past the eternal torture of the victims living in his own mind little else could move him. I would argue he must already have started down this path to cause the torture in the first place * Cognative dissonance: If he hasn't sank to entirely inhuman levels of disinterest in the pain of others the only way to do this is to completely separate the two beliefs and worlds. Perhaps he tells himself the pain he inflicts is necessary and part of a greater good but doesn't believe anyone else should have the same right. * A separation of the self: multiple personality disorder. Here he could tell himself there is some evil within that causes the torture that isn't the 'real' him, that he separates the actions he takes to preserve himself and his day to day life and calls them different people. * Religious belief: Perhaps he believes that what he does is to free the souls from their bodies to be judged by a God...if they're deemed worthy then they're returned to the body otherwise they're held and tortured in hell. The screams he hears, he tells himself, are only of those that God believed should be punished. It would be interesting to see others in your world deal with this. Is the torture truely necessary or could another sorcerer first find out how to trick the souls into believing they're in another world, something akin to the matrix, where they're still under the belief they they're alive and so the torture doesn't reach them and the sorcerer wouldn't go insane. Perhaps their pleasure is as much a source of power as their pain, only their pain is easier to extract. --- P.S For clarity the high brow, classic source which inspired the last thought was the early 21st century work of art known as [Monsters, Inc](https://en.wikipedia.org/wiki/Monsters,_Inc.). ]
[Question] [ We have a variety of ways of describing our location here on Earth. We can refer to a nearby landmark (eg "by the City Hall"), we can describe our location relative to an area (eg "in the South of the island") and we can describe our location with Longitude and Latitude. It is the later of these methods I am interested in, but on the scale of the Universe. Obviously the Lat/Long system works because we have identified the North Pole, the South Pole and the Equator of the Earth. This allows us to give 2 arbitary numbers to locate any point on the globe. I am imagining that to have a similar coordinate system in the Universe we would also need to mark out some absolute points. Given that everything in space is always moving, what could be used as an absolute point in the Universe? The Big Bang perhaps? I considered having the observer as an absolute point, but I am unsure how this would create a reliable coordinate system that could be transfered to another observer. Whereas the Lat/Long system only requires 2 coordinates, I can imagine a Universal Coordinate system would require at least 3 coordinates. I have been considering adding time as a 4th coordinate, as everything is in a state of motion, knowing the time might help work out relative points if no absolute points can be found. In general I am struggling with how a Universal Coordinate System would work. Simple X, Y, Z coords (with 0,0,0 being Earth?) seem insufficient in a medium that is in a constant state of change. Has anyone else tackled such a system? [Answer] [Pulsars](https://en.wikipedia.org/wiki/Pulsar). Observe the [Pioneer Plaque](https://en.wikipedia.org/wiki/Pioneer_plaque): [![Pioneer Plaque](https://i.stack.imgur.com/t5d0S.png)](https://i.stack.imgur.com/t5d0S.png) See that bunch of radiating lines on the left? That's a remarkably good way to identify where (and perhaps even when) Earth was when the space probe was launched. The patterns on each line represent the pulses emitted by a particular pulsar. There's some additional fiddliness here caused by the need to encode it in binary and include a way to describe the time period being encoded, but that's for communicating with aliens and you don't need to worry about that. Because each pulsar is uniquely identified by its period, you can describe your location in terms of the angles between various specific pulsars which will effectively pin you down in space. You don't even need to know how far away the pulsars are, which is nice. Pulsar positions will drift over time, and their pulse rates will decrease, but those timescales are long and if you only need to have a location that's good for a few thousand years you'll be just fine. Beyond that it'll still be traceable by anyone who has got a good model of pulsar spindown and orbital motion about the galactic centre, though without also knowing your velocity and heading (which you'd need to encode separately) they wouldn't know where you ended up. Multiple solutions may crop up as one pulsar slows down to the point where its period precisely matches that of an ancient pulsar used to define a location, but handling that is a Simple Matter Of Mathematics, of course. The system can be made universal, but the position will be in terms of the pulsars in a particular galaxy. You'd need some completely different way to describe the position of your galaxy in terms of other galaxies... SRM suggested [Quasars](https://en.wikipedia.org/wiki/Quasar) which could work, though they lack the signature pulse rate that makes identifying specific pulsars relatively straightfoward. Honestly though, if you can manage easy intergalactic travel and communication, you'll be able to find someone or something who can think up a better navigation scheme, as near-godlike powers will be required to cross intergalactic distances in any reasonable length of time. [Answer] Orbital Mechanics! It's not a simple topic, but it's worth your time. They're basically the 6 numbers required to describe the position in time and space of an object orbiting another object. So, the takeaway from that is if you want to describe the position of an object in space it'll need to be in reference to another object. That could be the galatic center if you're describing a solar system (or a spaceship in interstellar space), or the closest planet if you're describing a moon. And they'll need to be nested if you're describing the position of a moon around a planet from another galaxy. --- Why orbital mechanics? ## Because there are no privileged frames of reference in space. The Orbital Elements... To mathematically describe an orbit one must define six quantities, called orbital elements. They are ``` Semi-Major Axis, a Eccentricity, e Inclination, i Argument of Periapsis, ω Time of Periapsis Passage, T Longitude of Ascending Node, Ω ``` Their details require a bit of book learning I won't copy-paste here, but they're available lots and lots of places (wikipedia, your local library, your local astronaut, "SevenEves" from Neil Stephenson). ]
[Question] [ Vocal mimicry for this question refers to the ability to imitate the sounds of other animals, exemplified [in this video of a lyrebird mimicking several species of birds, a chainsaw and even a camera shutter](https://m.youtube.com/watch?v=VjE0Kdfos4Y). The idea of a predator imitating the sound of a human voice is by no means my creation, Pliny the Elder claimed over 2000 years ago that [hyenas could imitate human voices with the intent to deceive and kill](https://en.m.wikipedia.org/wiki/Crocotta). So with the fact that there is an animal in nature with incredible vocal mimicry and that legends of monsters with vocal mimicry I am therefore quite curious on how feasible of a tactic this would be for a large predator. My logic is that a predator could mimic the calls of various prey items than it would be able to lure prey close enough for it to pounce on them. So would vocal mimicry be a good hunting tactic? Might a predator with lyrebird like vocal mimicry be able to lure everything from elk to humans into its clutches? Bonus: Would it be feasible for this predator to be a mammal, or is a large bird more feasible? [Answer] Absolutely. Mimicry in itself is one of the key strategies for prey and predator animals, and while audial mimicry is rare, it also happens. Mostly certain insects like cicadas hunt in this manner, but a feline species called the margay hunts with this tactic - pretending to make the distress call of a baby a certain monkey species, luring its prey towards it. Other than that, there's the obvious example of us humans using various hunting lures to hunt. I take it that by large predator you mean something like an apex predator of not just a part of a jungle but the entire jungle, something like a tiger or a bear? Scents are a huge defensive tactic by many animals, so you could take that into account when designing your creature. How smart is the predator, how smart is the prey? Does the predator have a certain odour, does its prey have the sensory organs to sense it other than through hearing? What about eyesight, reaction speed, etc. You could also take into account how it'll move and hunt. Does it keep its distance and then swoop in to catch its prey, like a hawk, or does it lay still and camouflaged until its prey is close enough for it to strike, like a snake? Is it a pack hunter, constantly following and guiding the prey to its pack by making "safety" calls, or maybe it stalks after until its prey tires out, all the time making "safety" calls? To surmise, when it comes to audial mimicry itself, it's mostly used as a defensive tactic by prey to avoid/fool predators, but yes, aggressive audial mimicry makes sense and could absolutely be a tactic. [Answer] As it happens, I know of a predator combining vocal mimicry with other forms of mimicry. This is so horrendously effective that it can infiltrate the colonies of its victims and remain undetected while killing and eating their children for nearly a year! During its lifecycle, it will consume on average 1,200 prey from the colony it targets. What kind of horrific predator could succeed in doing this? THIS ONE: [![Image taken from Wikipedia, https://en.wikipedia.org/wiki/File:Maculinea_arion_Large_Blue_Upperside_SFrance_2009-07-18.jpg - Creative Commons 3.0 license (https://creativecommons.org/licenses/by-sa/3.0/deed.en). Credit goes to Wikimedia user PJC&Co](https://i.stack.imgur.com/AA5LZ.jpg)](https://i.stack.imgur.com/AA5LZ.jpg) (This image was posted to Wikimedia under a Creative Commons 3.0 license - <https://creativecommons.org/licenses/by-sa/3.0/deed.en>. As per the terms of that license, credit is due to Wikimedia user PJC&Co) It's the Large Blue butterfly - Phengaris arion. During it's early life, the caterpillar is merely a herbivore, living on plants. However, after it has moulted three times, it falls to the ground and begins to secrete chemicals which mimic the pheromones of Myrmica sabuleti ants. At this stage, it has some physical resemblance to an ant larva, and foraging ants are fooled into thinking it's one of theirs that's escaped from the nest. They will carry it back to their colony, and put it in with the real ant larvae. The P. arion caterpillar, once it's safely ensconced in the ant nest, will go looking for relatively isolated chambers in which it can hide. After finding one, it spins a layer of silk which will allow it to hide at ceiling level. Every so often, it will emerge from this hideaway and venture into the "nursery", where it will eat several of the ant larvae. It chooses the largest larvae it can find to feed on, before returning to its hiding place. It may be as much as ten days before it ventures out again. Meanwhile, it's making sounds that mimic those of an adult queen ant. Combined with the pheromones it's secreting, this allows it to go undetected, and in fact to be accorded the highest possible status in the colony! That said, parasitic butterflies from the same family, such as Phengaris rebeli, are the ones which really exploit the difference in sounds between queens and workers. I think this one just needs to impersonate the ants in general. Essentially, what it's doing is 1. To eat the largest ant larvae it can - they provide the biggest meal, and it needs to eat them quickly before they pupate. 2. Then giving the workers time to fatten another crop of larvae to the same size. 3. And then emerging to consume them as well! 4. (Go back to step 2. And so the cycle continues.) Over time, the caterpillar may well end up eating all of the larvae in the nest. This causes the surviving adults to abandon the nest. After this has happened, the caterpillar waits for another, nearby ant colony to take over the abandoned nest. It can go without food for several days while waiting for this. On average, a caterpillar that survives until adulthood will destroy two host colonies by consuming all of their larvae, and will have a third colony of victims present in the nest when it finally pupates. During this time, it will have killed and eaten over a thousand ant larvae. That said, new colonies don't always expand into the nest, and the caterpillars sometimes starve to death as a result. During its lifecycle, the caterpillar will grow much, much larger than an ant larva. So visual mimicry is absolutely out of the question. It's got to rely on a combination of acoustic and chemical mimicry, as well as staying hidden. But eventually, it pupates. At this point, it can no longer secrete any chemicals, and bears no visual resemblance to an ant larva/pupa/adult. All that it has is a "stridulation organ" on the pupal shell, and this organ continues to imitate the sounds made by the queen. That is now the only from of mimicry it's doing - it relies entirely on vocal mimicry to survive this stage and reach adulthood. A beautiful butterfly - or a horrifying monster? From the viewpoint of the ants, it's the same thing! Sources - non-paywalled: [Barbero, F., Patricelli, D., Witek, M., Balletto, E., Casacci, L. P., Sala, M., & Bonelli, S. (2012). Myrmica ants and their butterfly parasites with special focus on the acoustic communication. Psyche: A Journal of Entomology, 2012.](https://www.academia.edu/download/44035377/Myrmica_ants_and_their_butterfly_parasit20160323-24331-1uymt1a.pdf) [Thomas, J. A., Schönrogge, K., Bonelli, S., Barbero, F., & Balletto, E. (2010). Corruption of ant acoustical signals by mimetic social parasites: Maculinea butterflies achieve elevated status in host societies by mimicking the acoustics of queen ants. Communicative & integrative biology, 3(2), 169-171.](http://www.academia.edu/download/43543471/Corruption_of_ant_acoustical_signals_by_20160309-10016-h4o5f0.pdf) [Barbero, F., Bonelli, S., Thomas, J. A., Balletto, E., & Schönrogge, K. (2009). Acoustical mimicry in a predatory social parasite of ants. Journal of Experimental Biology, 212(24), 4084-4090.](https://jeb.biologists.org/content/jexbio/212/24/4084.full.pdf) [Barbero, F., Thomas, J. A., Bonelli, S., Balletto, E., & Schönrogge, K. (2009). Queen ants make distinctive sounds that are mimicked by a butterfly social parasite. Science, 323(5915), 782-785.](http://www.academia.edu/download/44035374/Queen_ants_make_distinctive_sounds_that_20160323-32481-1jpz4ep.pdf) [Thomas, Jeremy & Elmes, G. & Schonrogge, Karsten & Simcox, D. & Settele, Josef. (2005). Primary hosts, secondary hosts and 'non-hosts': Common confusions in the interpretation of host specificity in Maculinea butterflies and other social parasites of ants.](https://www.researchgate.net/publication/233912192_Primary_hosts_secondary_hosts_and_'non-hosts'_Common_confusions_in_the_interpretation_of_host_specificity_in_Maculinea_butterflies_and_other_social_parasites_of_ants/link/5db2bf60299bf111d4c8320a/download) [Thomas, J. A., Schönrogge, K., & Elmes, G. W. (2005). 17. Specializations and host associations of social parasites of ants. Insect evolutionary ecology, 479-518.](https://www.researchgate.net/profile/Karsten_Schonrogge/publication/224817203_Specializations_and_Host_Associations_of_Social_Parasites_of_Ants/links/564451e408ae54697fb6b8a3.pdf) [Thomas, J. A., & Settele, J. (2004). Butterfly mimics of ants. Nature, 432(7015), 283-284.](https://socialevolution.ku.dk/papers/2004/thomassettele2004_newsviews.pdf) [DeVries, P. J., Cocroft, R. B., & Thomas, J. (1993). Comparison of acoustical signals in Maculinea butterfly caterpillars and their obligate host Myrmica ants. Biological Journal of the Linnean Society, 49(3), 229-238.](https://cocroft.biology.missouri.edu/wp-content/uploads/2014/07/1993-DeVries-Cocroft-Thomas-ZJLS.pdf) Sources - paywalled: Thomas, J. A., & Wardlaw, J. C. (1992). The capacity of a Myrmica ant nest to support a predacious species of Maculinea butterfly. Oecologia, 91(1), 101-109. [Answer] one unifying bird-speak ism is a sharp short uptick in pitch as almost a single note slide "up"... just about all birds use this to warn -cross species- that there is something to be alerted about. The concept of Warning! would probably be more of a argument against mimicry, because stalking prey and warning your own species would probably be more of a chosen path of evolution. HOWEVER, taking that logic a bit further, if "WARNING" was used by a sympathetic species that is social enough to Usually save a fellow of \_\_ then a distress call would be Quite selected for in a predator... but then quickly selected out by the prey... I think the answer mentioning "Predator" with a prey species that's curious enough to investigate some weird vocal call (like snipers wounding a person in a field to then have others try and save the injured) might be viable, but dependant on a more Studied relation between predator and prey, irrespective of species type for either (bird like / mammal like / or even under water) [Answer] Blue jays use that tactic. They mimic red-tailed hawks to scare other birds to steal food, such as birdseed and eggs. Sources: <https://owlcation.com/stem/Blue-Jays-Clever-Mimics-of-the-Bird-World> <https://www.allaboutbirds.org/guide/Blue_Jay/overview> <https://www.allaboutbirds.org/guide/Blue_Jay/sounds> [Answer] You should carefully consider this creatures environment if its surviving off a mix bag of moderate sized animals and humans or the bulk of its diet just favors the human and large animals since you seem to want it to have the taste for human one then needs either a large roaming area to hunt in maybe crossing state lines (giving respite to highly rural locations lowers their suspicions) but the pit fall in doing this is that once the boondocks is taken out no one is eager to move there no roads, no power, ect tend to not attract many folks to difficult areas so now your looking for areas that get sporadic traffic like trails, hunting seasons, and gold/resource mining areas to feed this thing year round. The size should also be considered and its digestion how long can it last without humans or other feed? Can it go a month or more between feedings or not? Craft this thing with the environment, it's physiology don't try to squeeze it into just one known mythical or real creature figure out what it needs before aesthetics then graph its habits to help make the right monster for your novel. It could learn words yes have you seen the video of the cat asking, "Are you coming down?" scared the owner. Foxes can sound like screaming women or the peacock screams, "HELP!" if you don't know these things can do any of these sounds then yes you might run into that peacock or fox but your predictor is banking on an altruistic person when the society it hunts in becomes cold hearted cries for help are no longer investigated it will need to adapt. I'd day the thing in question might be a pair one calls the other traps and kills they both share it. Because once the human figures out where the sound is coming from and sees the creature its attached to their tendency to flee or fight is going to occur a group or paired assault would be the best attempt no matter the size or shape of the creature to kill the human. If your predictor is a stalker type it could observe a group of prey learning their voices, relations, and habits and pick them off sometimes at range other times at the home. When the family members/group/pair are desperately missing their missing member they might be tricked for a brief duration outside if the person calls them and knocks on their door or shouts at the edge of the woods but if the family inside is paired up there is a small risk one may stop the other. If the area is rural there maybe little to no witnesses to spread the word of the human mimicking creature to others but in small towns or cities there will be. ]
[Question] [ Leaving aside the matter of how well would humans fare on the surface of Mercury (we only have to factor in the weight of their life support: air, water, food and spacesuits), and assuming materials and methods available today, would it be possible to come back from Mercury once you landed? You'd have to either carry the fuel to thrust away from Mercury and the Sun or to produce it locally (if it's possible to produce the fuel locally, we can assume any number of previous one-way missions taking the necessary machinery to Mercury, and the crew of the return mission would only have to assemble and operate such machinery). The B-side of the question: how much would it all cost, very roughly speaking? Finally, if there's no way of making it, is there any current research being conducted on something that would hint at promising the possibility of such a trip? What research would that be? [Answer] Assuming an Apollo-style mission (two-stage lander, with return vessel holding in orbit for return), this mission would just about be possible, physically, with today's rockets. Humanly, it's not possible at all. Mercury is the hardest place in the Solar System to reach, saving only the Sun itself, in terms of the universal currency of space travel, Delta-V. You have to nearly kill Earth's orbital velocity to fall down that close to the sun, then you have to almost match velocity with Mercury to make orbit there (and without any ability to aerobrake as is often done with Mars). Your lander will be heavier, as it takes much more rocket power to reach orbit from Mercury than from our Moon -- and the descent stage has to carry that larger ascent vehicle to a safe landing on rockets only. You might wind up with a lander resembling the SpaceX Starship and Starbooster just for your lander. And at the end, you need to have enough propellants still in the transfer vehicle to return to at least an aerobrake at Earth. The mission will take a minimum of several months, and the launch mass would be equivalent to at least four or five Saturn V launches. Alternatively, to get a mission you could launch on a Delta IV Heavy or Falcon Heavy, the return vehicle would be too small to carry even a single human, and even then you'd have to use multiple gravity assists from Earth and Venus (and probably at least one from Mercury) to substitute for lack of fuel -- and the mission would consume years each way, instead of months. The major objection to sending humans to Mars is trip time -- with a multiple gravity assist trip to Mercury, the trip time would be several times longer. Bottom line, nuclear propulsion (either a nuclear-thermal rocket of some kind or an Orion style pulse drive) would be the only way to send the necessary lander there and bring the crew back in a reasonable time frame. [Answer] If Project Orion type nuclear pulse engines count as "current rocketry", then if the political will to use them is present, a few years of research and development should suffice to build spacecraft more than adequate for a manned mission to Mercury and back to Earth. <https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)>[1](https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)) [Answer] Physically, we have almost all the technology needed to do it right now. We don't need hypothetical engines or gigantic new launch vehicles. We can build the main vehicle in orbit, much like how we have built the International Space Station. We would have multiple launches using heavy lift launch vehicles, like the Falcon Heavy for example, which would deliver modules to low earth orbit. These would be sent up empty, assembled together, and stocked and fueled just before the journey. There's no physical limit as to how big the whole craft can be, the only limits are financial. [Answer] It would be very hard to send humans to Mercury and bring them back to Earth using today's technology, but it could be done. If near term technology is included such as the Starship / Superheavy rocket being developed by SpaceX, it should be a bit easier. When they become operational it should be possible to ship many thousands of tons of propellant and rocket technology into low Earth orbit and build and or re-tank the ship there. One thing that would be essential is propellant production on Mercury itself. There is water ice and cryogenic temperatures in some of the deeper craters near Mercury's poles and ample sunlight and heat not far away so that should be relatively easy to arrange. ]
[Question] [ In the current setting I'm working on, I have an idea for a society of non-human (but still humanoid) creatures who evolved from territorial, mostly independent predators. Even though they are now intelligent, they lack a social affinity and are not predisposed to organise with each other in strict ways. As a result, their overall society is non-hierarchical and consists of small egalitarian clans that are bound together for mutual interest and mutual protection from outsiders. They have no single leader or even really a political system besides convincing others to come with them and do whatever they think needs doing. I guess you could call it a direct democracy of sorts. However despite being egalitarian to one another, they generally consider humans and other non-human species to be inferior and while a direct 'national' effort at conquering and colonisation is impossible, multiple of their clans have started leaving their lands with the intent to conquer settlements and towns and make them part of their disconnected society. This is not supported by all of them but none of those abstaining from this are doing anything to stop it. I guess what I'm asking is if it makes sense for an internally egalitarian society that contains few internal hierarchies to have a big external one that places everyone who isn't them at the bottom? If you don't really have a social concept of 'ranks' or who is and isn't in charge, can imperialism manifest from a sense of racial superiority alone? [Answer] No Imperialism requires complex organization, which your society explicitly lacks. Without internal organization they would never be able to create a functioning state, let alone wage wars of imperial aggression. There is a reason why anarchism has been relegated to tiny communes, the most primitive of hunter-gatherers, and supremely short lived militant occupations. The egalitarians could certainly be hateful and hostile to other species, and might kill them individually given how they evolved from territorial predators. There’s no reason why they wouldn’t necessarily hate outsiders, but their inefficient social organization would probably keep them only about as dangerous as packs of wolves [Answer] Faith and a caste system What they lack in social skills, they make up for in their faith and what they’re calling is. Let’s say when one of these non-humans, are born. They are marked and that mark gives them a role in there clan. Like this one is born with a red spot, he will become a good fighter; green claws she’s the next priestess for our clan. There are no leaders just the calling from there higher power. this will help them against races that have that social edge. THE CALLING When one of then gets the calling they will comply. Like so sort of force they flock to a location or do some sort of action to prove there faith. Many of there number join together under a single calling. That calling forms a clan many clans join together that makes a war band. That’s maybe why they felt compelled to expand in an organized fashion and why some believe they are superior. [Answer] Sure, happens all the time; barely an inconvenience. There's been lots of human non-hierarchical societies of various shapes and sizes proposed over the years, although most of them have not been implemented. Almost all of them put humans at the top and all non-human species somewhere beneath them. > > Genesis 1:26: let Man have dominion over the fish of the sea, and > over the fowl of the air, and over the cattle, and over all the earth, > and over every creeping thing that creepeth upon the earth. > > > The alternative -- putting humans on the same level as chimpanzees and dolphins and hagfish and planaria -- is much more unusual, but not unheard of. [Answer] There will naturally be some internal hierarchy no matter what. Surely some people will propose convincing decisions more often than others; these people could be reasonably said to be leaders. With this in mind, it wouldn't be that far-fetched for this society to have aggressive military goals. This is, roughly speaking, what the Vikings did in their early raids. Some ambitious person would round up as many volunteers as he could, and they'd go raiding. Some of their victims would be conquered outright, or become client states. Sounds pretty imperial to me. This did come about more from greed than racial superiority, but I think racial superiority would only make it more likely. [Answer] The answer will be in another question? Is there any Existential threat to them? In animal kingdom or in human society, people stay together only to overcome the existential threat. When threat is over, no matter how strong the social hierarchy is, it is destined to be fall. Be it Caste system, Religion or Nation states. (this is my personal opinion) So, in your setup the species is already intelligent enough to sense the threat and they are already making clans. They also have some sense of superiority, so high ego. I suppose they are also capable of waging war and have developed taste for blood. Let's say if humans start a campaign to stop these beast from taking their lands and if these beast suffer big loses, they would start building hierarchy, leaders will emerge, there will be some internal clash but they will become "perfect" nationalists society in no time. [Answer] > > (...) internally egalitarian society that contains few internal hierarchies to have a big external one that places everyone who isn't them at the bottom? > > > Focus on > > (...) few internal hierarchies (...) > > > Reminds me of mongols. Genghis Khan ([this one](https://en.wikipedia.org/wiki/Genghis_Khan), not [that one](https://www.youtube.com/watch?v=NvS351QKFV4)) is mostly known for being the emperor of one of history's greatest empires. If you follow the first link and get to [the part about his early life](https://en.wikipedia.org/wiki/Genghis_Khan#Early_life_and_family), you will see that he had been a hunter-gatherer, then a slave, before going on to be a warrior and uniting the mongol tribes. By that time the hierarchy of the clans was really flat - a clan had a leader, some warriors, and then mostly everyone else. --- For a non-human source of inspiration, see Argentine ants. Their hierarchy is also very flat and they wage some mind boggling wars among themselves - however, when expanding to new territories, clans cease hostilities among themselves and unite against all other ant species and even other kinds of animals. Kurzgesagt has an awesome videos on this: * [The Billion Ant Mega Colony and the Biggest War on Earth](https://www.youtube.com/watch?v=cqECNYmM23A) Check the 3:45 mark. [![Map of the world showing where Argentine ants have megacolonies](https://i.stack.imgur.com/1tiYq.png)](https://i.stack.imgur.com/1tiYq.png) The red blobs are where the ants lived a few decades ago. The parts with crows are recognized local megacolonies - but regardless, all those ants belong to a single global colony. They've lost the Southeast US branch to a megacolony of another species in the 20th century, but they still got the largest global colony in the world. [Answer] I think there is a lot of confusion here. For example you say non-hierarchical but then later you say > > their overall society is non-hierarchical and consists of small egalitarian clans that are bound together for mutual interest and mutual protection from outsiders > > > This is actually 100% a hierarchy. A hierarchy in it's most basic from is simply saying A is above B or it's better to do A than B. Merely placing an action or idea above another. And any form of society or even intelligent existence will have a hierarchy or sorts. A predator is pushed by his nature to hunt when it needs to feed. So the hierarchy here is continuing to exist is above expanding effort. But it also makes tactical decisions all the time. For example when hungry but confronted with a dangerous group of animals that can cause it harm it might back off because here getting the prey might mean dying. So I simply don't understand how can you even have an smart creature without that. Because ask a person in that "low" level society why they are together he then will answer because it's better than being alone. This is hierarchy. Now hierarchy can also be based on: strength, wisdom, or speed or whatever. It's not a fixed thing. So what is going on there? You also mentioned > > can imperialism manifest from a sense of racial superiority alone > > > Which seems like an odd point. Imperialism is about power and influence. They can be built on anything from being power hungry to plain old madness. But the thing is a society is a complex thing and you simply can't say that every single officer in the British army believed the same exact thing, nor that every single citizen of the Alexandrian "empire" did the same. So you have a ruling class and then social norms and so on. But imperialism is about actual power and that is different. So I guess I'm saying I think we need to know more. Because like it is said here: you can't have a powerful society with a lot of working together. Now I think house Telvanni of The Elder Scrolls universe might be something that helps? And I think what you mean is do they themselves need to work together in order to gain power? Well. You can build this society as something like 1 family of race A holding power and dominance over races and people. So you can incorporate extreme aversion to working together. For grimdark points you can have the leading male, or you can have it females whatever, murder any males offspring to continuing dominating the family. So a single family with a head will rule lands and hold power over a bunch of people. How much can that be pushed? Well. Not as much as if you put 3 families with their combined power together. They will create a mega family and congrats. You just rediscovered civilization. However humans are very malleable and once we figured out it is better to cook food than eat it raw we all got in on the action. Same with erecting huts together and dealing with our smelly neighbors but with the trade off of being protected from the elements and dangerous animals. But if we assume your race is unchanging in that regard then you can get away with something like I describe. But intelligent life would, likely, form a loose confederation of families because here is what is going on. Lets assume your race is very powerful. At a certain point there would be no more land to conquer and no more resources to fight over. The power of each family would reach it's absolute maximum expansion and by that point the smaller families are done. Now either risk fighting a war with another major family over a high risk high reward idea such as controlling their land, but also risk another family gobbling you both when you are weak. Or form a sort of non aggression pact with them and hold you influence in a state of continued vigilance lest a nearby family tries to conquer you. But before that if a new threat emerged then you will just have to also handle that. Assume family B have a lot of good farm lands. A human upstart is rebelling. What to do? You can ignore it. But it won't be long until that humans controls their lands and comes for you. You can risk trying to get in on the action. This could pay off and it could actually backfire. Or you can lend them some help to squash the rebellion and insure that humans serfs know their place. This is the best I can do. They don't work together and 1 leading figure holds much power. But they are not stupid. However this is a form of monarchy but with less of their own race. There can be a lot to be said about this but assuming that it even relevant. Anyway Obviously the world of politics is complex and decisions need to be made. Cooperation is essential for any empire. Now magic can actually change that. But it's not mentioned. And like I said I think we need to know more. Especially defining what you mean by those terms. ]
[Question] [ I'm positing a non-planetary world but within Euclidean space. This world has things that resemble mountains (but probably not plate tectonics). Elevation varies considerably, but on average it is perfectly flat as far as any inhabitant could tell. If they were to do the various experiments Flat-Earthers should do, they'd discover that their world wasn't spherical. Inhabitants experience "falling" which gives approximately 1G of acceleration. But if the extent of the world is infinite, true gravity would have collapsed this into some sort of singularity, so it's probably not gravity as we know it. There are no stars in the sky, or any typical astronomical bodies. This causes a deep black darkness which is only broken up by a strange phenomenon... appearing out of the eastern sky is a giant fireball that streaks across the sky to the west. It is visible for a long time as a faint bright dot (the inhabitants call these stars) before it appears directly overhead (or close enough to it) to provide a period of several hours with "daylight" and warmth. When it is overhead it will appear far larger, but as soon as it does it starts receding into the western sky where it is visible as a "star" once more. If this world has periodic day/night cycles of approximately 24 hours, can anything be inferred about the size of the "sun" or its altitude? For how long will the eastern and western stars be visible in the night sky before they're too faint to perceive with human eyes (assuming no obstructing mountains/elevation on the horizon)? How far north/south can one travel before it is perpetual night or they freeze to death? Are future suns visible in the east during daylight (and past suns in the west)? How fast do these suns travel? What color are they, can they be roughly the color of our own sun? How much can any of these things vary without the people on the surface being wiped out (either by a sun flying too low/slow and frying them, or their world freezing, etc)? [Answer] The apparent magnitude of the sun as seen from Earth is -26.75; when a celestial body with this brightness shines we consider it to be 'daytime'. Conversely when the full moon (magnitude -12.74) shines, we still consider it to be 'night time'; the sun is 400,000 times brighter than the full moon. Since apparent magnitude follows an inverse square law with distance, this means that 12 hours after midday, the passing sun is at least 632 times further away than it was at perihelion; actually slightly more because there will be two moon-brightness objects in the sky (one advancing and one retreating). You can increase this ratio for a darker night. We still don't have a fully-constrained problem in terms of working out the distance to the 'sun highway', but we can still put an upper bound by assuming that we still have the speed of light as a universal speed limit. If the maximum distance the suns can travel (relative to the observer) between midday and midnight is 12 light-hours, or 86.5 AU (about the diameter of the solar system out to the Kuiper Belt), then the maximum distance at perihelion is only about 20 million kilometers (0.14 AU), much less than the orbit of Mercury. In order to remain habitable, the suns need to be much more compact and cool to still provide a non-cooking amount of illumination. At that distance, though, you could travel for hundreds of thousands of kilometers away from the 'equator' before any noticeable change in radiance, or even a perceptible change in the inclination of the suns. If you shrank the system by a factor of a hundred, though, so perihelion is at 200,000km (half the distance from the Earth to the Moon), and suns shot off (at $\mathrm{3000\ km\ s^{-1}}$) to a distance of 0.87AU, then you'd see a 1% change in brightness after the first thousand kilometers away from the equator. Working out what that would translate to in terms of climate and weather patterns on a flat world is a much more challenging question. [Answer] The inhabitants can calculate the height of the “star” by using simple trigonometry with people positioned at different points in its path and synchronized watches. Knowing its height the size of the star can then be calculated by measuring its angular diameter and again using trigonometry or even simpler similar triangles. It is impossible to say how close or far these stars could get. It would depend on the exact number, their frequency, temperature, speed, altitude, diameter, atmospheric properties and much else. [Answer] Since Newtonian/Einsteinian physics clearly don't apply here, I see no reason these "stars" and "suns" couldn't be actual hydrogen-fusing stars, just flying across the (infinite?) flat world at a (handwaved) speed and (handwaved) density such that they provide the day and night cycles. If they stars have the same population distribution as those in our universe, there will be many more of the smaller, cooler ones than there are of the very large, extremely hot ones, but since physics isn't involved here (maybe it's all magic?), there's nothing preventing these stars from flying at altitudes determined by their mass, such that their light and heat as seen at ground level is nearly constant from one to the next. Of course, there's also no reason they need to be what we'd call stars. They could as easily be flying balls of combusting coal, chariots carrying various gods, or immense, cordless spotlights flying through the sky. Since you've thrown physics out the window, you can make up whatever seems good to you. ]
[Question] [ Humans have colonized the subsurface oceans of [Europa](https://solarsystem.nasa.gov/moons/jupiter-moons/europa/in-depth/) - building large cities embedded in the icy crust, [hanging beneath it](https://worldbuilding.stackexchange.com/questions/119340/hanging-city-on-europa-is-it-feasible), and resting on the rocky seafloor. These colonists mine metals for construction from the mantle and harvest [local fauna](https://worldbuilding.stackexchange.com/questions/165815/how-big-can-europan-fish-get) for food - but where do they get their air? Known resources: * Europa has a thin oxygen [exosphere](https://www.sciencedirect.com/science/article/abs/pii/S0032063315003165). * The ocean is mostly water, and it's [salty](https://www.scientificamerican.com/article/water-on-europa-with-a-pinch-of-salt/). * The seafloor is [in contact](https://europa.nasa.gov/resources/113/interior-of-europa/) with a rocky mantle composed of mafic rock. * [Hydrothermal vents](https://en.wikipedia.org/wiki/Hydrothermal_vent) produced by [tidal heating](https://en.wikipedia.org/wiki/Tidal_heating) are common, and they release Earth-analogous minerals into the water. * The ocean is enriched in oxygen due to [radiolysis](https://phys.org/news/2009-10-jupiter-moon-europa-oxygen-life.html) and crustal ice circulation. * Fusion technology exists, so fusion-associated helium isotopes are available * Resource can be imported or mined off-world but only if no cheaper alternatives exist What resources would be most efficient to draw on in order to create air breathable for whole lifetimes inside the colonies? Oxygen seems abundant, but assuming many of the submarines on this world will be pressurized, colonists won't want to risk oxygen toxicity. Thus, other gases need to be mixed in. What resources can be drawn on most efficiently and combined to make breathable air? One starting point might be looking at [breathing gases](https://en.wikipedia.org/wiki/Breathing_gas). CLARIFYING EDIT: Oxygen is abundant, as evidenced by the list of resources above. I'm looking for an answer that specifies how to achieve a healthy atmosphere beyond just getting oxygen because just oxygen is poisonous. How can other complimentary gases be harvested? [Answer] It seems very likely that Europa has a vast subsurface salt water ocean. Such an ocean would in all likelihood contain some nitrogen as dissolved gas, nitrate or ammonium salts or other more complex amides and amines. Such chemicals could be processed to release the nitrogen for use in a habitat. The exact method would depend on the form that nitrogen takes but unless it occurs at a very low concentration and requires a lot of work to concentrate it, it should be relatively easy to extract via an appropriate molecular sieve or ion exchange method. Oxygen is also likely to be dissolved in the ocean and might be released just by applying a vacuum. If this did not produce enough electrolysis could be used to split water into hydrogen and oxygen. I very much doubt that the local fauna would be on the menu. Having a separate biogenesis and evolutionary path in an environment significantly different to the earth (ocean depth, lack of significant atmosphere and gravitation for instance) it is highly unlikely that the same biochemistry found in life on earth would be replicated. There might be some similarity in some molecular reactions but there would in all likelihood be many variants some toxic to human life in the same way that random organic compounds from a lab might be toxic. For example would life be based on DNA or use pentose sugars? Would it use the same amino acids? Would they be the same handedness? How much of [this](https://www.sigmaaldrich.com/technical-documents/articles/biology/interactive-metabolic-pathways-map.html) would evolve in the same way on Europa? [Answer] Cant you obtain a starting supply of oxygen from water itself via electrolisis? I dont know if its the best way to obtain it, but its a way. And you still have to get the rest of the gases to get the atmosphere. Once there, you can get oxygen and food from hidroponic farms (I guess they are not consuming ONLY local fauna) [Answer] There are various methods out there, some more effective than others. 1. Extract diluted oxygen. There's always air in water, its a given. You would generally extract the air shaking the water, causing the air to escape. That being said, this is not turning water into air, its just removing air that's already there. 2. [The Electrolysis Approach.](https://m.wikihow.com/Make-Oxygen-and-Hydrogen-from-Water-Using-Electrolysis) Popular as a science fair experiment, this method uses electrodes to add large amounts of energy to the water. This overloads the water molecules, causing the water to separate into hydrogen and oxygen. While this is a very cool and science-y approach, it does have one problem: Water by itself does not conduct energy very well, its the salts in the water. As a result, you have to add salt to the solution in order for this approach to be effective. Unfortunately, this salt breaks down into chlorine gas during the process, poisoning the resulting air. It is possible to filter out the chlorine, but it would be too expensive on a large scale. 3. Boil the water. You know those bubbles in boiling water? Those are air bubbles made from the breakdown of water molecules. This approach is almost as effective as electrolysis, but without the chlorine. If I were your hypothetical colonists, I would use this approach, as it also solves the problem of heating the colony. All in all, this is the best approach. ]
[Question] [ In the game Monster Hunter World, there is a place called the coral highlands. The coral highlands is one of the most spectacular things to look at in the game, having a resemblance to a ocean without the salty water, or any massive bodies of water at all except ponds and rivers. The coral highlands are filled with massive corals, anemone-like trees and grass; the life forms there have some traits akin to real world sea creatures, like little glowing, floating creatures that look and act like little jellyfish, creatures known as wrigglers which act like little fish in the ocean and are known to dig communal holes, and many many more. The environment itself does have a lot of ledges and tall hedges and many strong winds. This, however, got me thinking: 1. Is it feasible for a place like the coral highlands to exist? 2. If not, could it be made in a lab setting? --- Edit: In the game there is also a location called the rotten vale which is located right under the coral highlands. It is littered with dead bodies and rotting corpses, and it is said that it nourishes the coral highlands itself. I wanted to include this because it might help with feasibility. [Answer] The reason there are so many sedentary (non-mobile) sea animals, including corals, sponges, barnacles and anemones, but no sedentary land animals (apart from parasites), is because water can carry a lot more biomass in it to feed them. Water is filled with plankton, tiny fish and jellies, and floating bits of dead plants and animals, so a sea creature can survive by letting food filter through its body. On land, there simply isn't enough food flying around to make this lifestyle worthwhile, so the only sedentary land organisms are plants that live off of the sun. Organisms don't need to evolve to float in water - most organisms are made of mostly water, so they float by default. But to float in air, an organism needs to evolve specifically to do so - and the benefits of unpowered flight aren't significant enough to warrant this happening on a regular basis. To make true "land coral" viable, you're going to have to find a way of putting a lot of biomass into the air. One possibility are these little floating "air jellyfish" you mention - perhaps they are the largest of their kind, and there are many other lighter-than-air, minuscule creatures floating around. If there are large amounts of tiny, lighter-than-air floating creatures, they might be able to sustain a forest of coral. The real question is, why do these air jellyfish exist? The only thing I can think of is that some of them are actually plants, and they ride the air currents up into the upper atmosphere to gather more sunlight. [Answer] Instead of trying to "drain the ocean" to get the Coral Highlands, why don't we just have it evolve analogously to a water biome, but be based on more "normal" land creatures. It may be called "coral" but what if it just looks like coral? The tiny critters (polyps) that live in the structures could be crepuscular or otherwise spend most of their time hiding in their constructed shells. Maybe they're tiny little crab-like creatures instead of squishy polyps, something a little more conducive to land life. [![The Coral Highlands](https://i.stack.imgur.com/yu5xx.jpg)](https://i.stack.imgur.com/yu5xx.jpg) Coral shells are made of calcium carbonate (limestone). Bones are comprised in large part of calcium. I think we can work out a way for the bones in the valley below to feed coral "reef" building up high. We just need a creature to break down the bones and excrete the calcium somewhere for the polyps to consume. I don't remember the creatures of the Rotten Vale very well but I know there are several very nasty ones that could believably feed on bones and produce the calcium as a waste product. Maybe they want the collagen or marrow instead, which is extremely nutritious. [![The Rotting Vale](https://i.stack.imgur.com/Uv5vu.jpg)](https://i.stack.imgur.com/Uv5vu.jpg) So we've got the coral formation generally covered. Now let's look at some of the other critters. @IndigoFenix mentioned the jellyfish being more like floating plants. In effect that's not far from what jellyfish actually are if you look at function alone. They kind of hang around waiting for their environment to just give them nutrients. There are plenty of questions/answers out there about floating plants, [like this one](https://worldbuilding.stackexchange.com/questions/11208/are-flying-plants-possible). The trees that look like anemones are easy enough, they don't need a reason to have evolved that way, as long as they still function more-or-less like trees we're used to. Maybe they could be predatory too, like an anemone. Think of a giant pitcher plant or other predatory vegetation. The wrigglers might be a little tricky because nothing can really move through dirt like water. Even moles, some of the best diggers, can only go at a max of [15 feet per hour](https://wdfw.wa.gov/species-habitats/living/species-facts/moles). I don't really have a good solution here. The dirt could be very loosely packed, but that creates problems for other critters trying to walk on it. Maybe the wrigglers could stick to areas of very boggy terrain that would be easier to dig through. In conclusion, while it may not have evolved literally from the ocean, we can still come up with pretty good analogues using land-based creatures. Could evolution have directed this? It's possible. Could it have been directed in a laboratory setting? That would be a huge lab, but I don't see why not. Edit: Final note, having the Rotting Vale feed the Coral Highlands isn't a big stretch. You just need a vector to transport the nutrients from one place to another. With the wealth of creatures around and the ability to create your own, it shouldn't be difficult to designate some things as scavengers that transport materials as they search. [Answer] I believe this is possible, but the rotten vale has to have a LOT of rotting going on, since we're going to need a lot of methane. The region's plants have established a symbiotic relationship with methane-consuming bacteria that grows into hybrid frond-leaves. [The sort of bacteria I'm talking about mostly live under the ocean.](https://learningenglish.voanews.com/a/small-organism-in-deep-sea-rocks-eat-methane/2490007.html) The coral structure comes from a the carbonate byproducts of the bacteria. The adaptation could have evolved from a direct evolutionary need for wind-resistant leaves. Normally, windy circumstances result in very small leaves, very flexible leaves, or no leaves at all. But, a plant which could have methane polyps attached would be able to grow a hybrid leaf mixed in with colonies of these methane-consuming bacteria. This enables retracting and extending the leaf (to protect from wind and/or conserve moisture,) and thus the tree would be able to have much larger leaves and gather more energy within a given space despite the wind. The methane bacteria aren't really producing any extra energy for the tree normally, and they sometimes require some energy from the tree if the methane isn't concentrated enough, but overall they carry their weight in terms of energy. The adaptation has proved useful enough that almost every plant in the region has created some sort of symbiosis with methane bacteria and exhibits some sort of anemone-like retracting action. On to the animals!!! The jellyfish things are the mature, breeding stage of development of a common small creature in the area. As the creature approaches maturity, it gathers methane-rich substances and then forms a colony. The colony then converts the methane back to a gaseous state and drops weight until it can float around looking for new locations to spread. Sizes of colonies vary, as the more methane-rich environments can support much smaller breeding colonies. Wrigglers are the juvenile state of the jellyfish things. The holes they dig are to try and find methane-rich deposits on the roots of various plants for use later in colony formation. They don't eat the roots, so this is mostly beneficial to the plants. ]
[Question] [ This question is based off videos of octopi running using their tentacles curled under and their body raised from the ground. <https://www.youtube.com/watch?v=23qzi88k3aM> I saw this question [Anatomy of a walking octopoid](https://worldbuilding.stackexchange.com/questions/143124/anatomy-of-a-walking-octopoid) but it is the specific running motion strong enough to lift the body up that I am after. I was wondering, for a design of a tentacled land alien what muscular anatomy would be needed to achieve something similar? The main body or head of the creature would be of a similar size to an octopus or smaller so there isn't to much weight to lift up, I was thinking an elephants trunk is pretty strong and accurate with its movement so something similar may work? would they need some strange gluteus/lower abdominal type muscle also? So my question is what anatomy would this running land octopoid need? [Answer] They would need very different musculature from humans and vertebrates in general, and the gait would also be very different. The locomotory tentacles - two, or three for stability, or four to leverage lateral symmetry - would of course need two or three strong antigravitational muscle fascias to keep the body off the ground and have it "fall" forward. They couldn't apply leverage to a bone or exoskeleton like vertebrate and arthropods do, but they would almost surely evolve a hardened surface (essentially a segment of exoskeleton) to improve grip on the ground; the muscles would then naturally bind to that. To improve flexibility they would have two or three hardened, corny "shoes" on the lower part of each tentacle, joined by flexible tendons. The gait would be either the awkward movement of clowns with too-long shoes, or more likely they would swipe the legs laterally (two other sets of muscles are required), keeping the tentacle tips bent inwards to reduce the footprint. The body would fall forward as humans' do, then the hindmost tentacle would swipe to the outside (or to the inside?), sliding forward with minimum elevation, and land on the ground to the front, taking the weight. Having only one section of tentacle as "shoe" would give a wobbly gait like walking on stilts. Having two would achieve a smoother gait, as weight shifts from the back to the front of the same tentacle "shoes". With two tentacles for motion and two others for stabilization, your alien would be able to run quite fast, sort of a low-altitude flight. In closed environments it could be able to navigate sharp bends at speed way better than a human could, using the other tentacles to pull and push against walls and other support structures. (a different gait with two slow "treads" under the tentacles of the alien gukuy is presented in [Eric Flint's Mother of Demons](https://en.wikipedia.org/wiki/Mother_of_Demons) - the cover image does not match the description). [Answer] Having seen several questions like this boiled down to "they cant without bones" you'd have to find some kind of intermediary solution. Example: you split the tentacles in a normal variant and a walking variant. The walking variant holds a spinal structure similar to a snake body, which we know can carry a lot of weight and exert a lot of strength for at least short periods of time. These walking variants would be less flexible but have strong placements for muscle attachment and the bone to carry a lot of the weight. The more ridgid you make the tentacles the easier and longer you can walk, up until you basically have an upper and lower leg. Various walking styles could be imagined. With 4 semi-ridgid walking tentacles they could alternate which 2 legs it walks on to rest the other two or walk on 4 tentacles simultaneously. With 3 you just use all 3 simultaneously. With only 2 semi-ridgid tentacles you could use the normal tentacles for balance, reducing the weight on the two main walking tentacles and pulling itself onwards. Edit: As a sure-fire option you could use what amounts to miniature legs. In the video you see the octopus walk on two tentacles, but they bend the tentacles so the tentacle is actually standing at it's halfway point. Two tentacles will get a femur, patella, tibia and fibula (upper leg, kneepad and the two lower leg bones) that take up the top half of the tentacle and are naturally connected to a hip-like structure in the main body. The lower half of the tentacle acts as a foot that seeks purchase on the ground, can offer stability and push off when necessary. We know with 100% certainty that this would be able to support the weight for extended periods of time as most creatures do this. The drawback is again that these two tentacles would sacrifice a lot of their maneuverability in the top half of the tentacle but it would guarantee the octopus the strength and stability (especially with help of the other arms) to walk around on land. [Answer] Long ago (a decade, probably two, so no references) I saw a show on discovery channel theorizing about how animals on other planets might look. One example they came upon, was actually land animals evolved from squids. Their solution for walking without a skeleton, was a series of ring like muscles around the leg, that would create a rigid cylinder looking like an elephants leg/foot. This structure would be able to create the necessary force to counter gravity and prevent the animal from collapsing under it's own weight. (an example would be how your tongue is able to extend, even though it has no bones in it) [Answer] You could simulate a skeleton using shell. [![nautilus](https://i.stack.imgur.com/cW5UL.jpg)](https://i.stack.imgur.com/cW5UL.jpg) <https://twitter.com/EdumacationAndy/status/1000834038075215873> Cephalopods are molluscans and mollusks have shells. Of extant cephalopods the nautili have excellent shells; depicted. Now imagine shellstuff which extends down each tentacle. The stick of shell transmits weight from the body shell down to the ground, and the stick is moved by the associated tentacle, which acts as muscles do for us. Shell material would bear the weight and be moved by the muscular tentacles. You could also have the shell simulate a endoskeleton and fortify the tentacles from the inside. The pen of a squid is a structure like this - the molluscan shell, acting as an endoskeleton. ]
[Question] [ Closed. This question needs to be more [focused](/help/closed-questions). It is not currently accepting answers. --- Want to improve this question? Update the question so it focuses on one problem only by [editing this post](/posts/162188/edit). Closed 4 years ago. [Improve this question](/posts/162188/edit) Most sci-fi stories depict aliens as humanoid; walking upright, having two arms and two legs, and a head on top. Sometimes the number of appendages varies, but they more or less resemble humans in overall shape. ### This does not seem realistic to me The likelihood of almost all intelligent, sapient life being humanoid strikes me as incredibly small, and is most likely put in stories for the sake of practicality and simplicity: * Aliens should appear or be described to move in a way that seems natural, something that might be difficult to express with an alien biology that does not exist in real life. * Humans interacting with non-humanoid aliens becomes much more complicated. For example, fighting scenes would need to be much more carefully planned. * By making aliens humanoid in shape, they can be portrayed fairly easily in fiction by human actors wearing costumes and makeup. For example it is much easier to design a character that is human in shape but has tentacles on his face than it is to design a squid-like character with a completely unique shape. I believe that aliens of near-human intelligence would vary widely in size, shape, and even basic anatomical functions. Even here on Earth, the variation is very high. --- ## How can I break down the task of designing alien commodities and items? For example, an intelligent squid species that slithers and slimes their way across the ground would not simply be sitting in an ordinary chair. These creatures would have developed their own versions of "chairs" or "beds" or "doors" or "ovens", etc. most of which would not resemble how we know them today. An interplanetary bar used by different alien species would almost certainly have a "bipedal" section, a "quadruped" section, and any other sections for housing the most common alien races that visit. This differs drastically from Star Wars, where literally everybody is sitting in ordinary chairs just like human beings would. A snake-like alien with human-level intelligence wouldn't have hammers, or basic tools the way that we know them. However, an intelligence of that level would enable them to have developed their own unique and fascinating ways of doing things. This should be breathtakingly different and inspire awe, which is what I'm striving for. But a giant snake holding a hammer in its mouth would arguably look stupid or comical. ### My focus here is trying to design the end-result of centuries of an alien race's ergonomic development. This is a very daunting task to me and makes me feel pretty overwhelmed. As long as the designs appear to be specialized for a certain race, that is fine to me. It does not need to be "perfect". Answers should: * Include any tips or strategies for designing alien commodities. I want a list of steps from people that have faced this problem before, breaking down the task into manageable sections that don't look daunting by themselves * Be detailed. Describe your approach to the problem so that not just I understand it, but other people who find this question can understand it too. * I don't want any opinions. Use examples, tell me how you have actually resolved these issues before. I don't want "maybe you could do this" answers, I want "Having run into this problem before, here are some steps that might help you and many others with this" answers. * Be generally well-received by the community. (will also be judged based on number of upvotes) The best answer will: * Have the most detail * Be intuitively or easily understood (should not require follow-up comments asking for clarification) * Be considered helpful (has upvotes) --- Please use [this helpful answer](https://worldbuilding.stackexchange.com/a/48/68902) to the very well-received and helpful question [How can I break down the task of creating a world into manageable chunks?](https://worldbuilding.stackexchange.com/questions/2/how-can-i-break-down-the-task-of-creating-a-world-into-manageable-chunks) as an example of what I am looking for. [Answer] Well, I guess I'll just use the same kind of answer as last time. *Step 1: Assume they aren't going to be that* different.** Both the 'basically-human' aliens and the 'Cthullu-esque uncomprehensible' aliens are fun tropes to play around in science fiction. The truth, unfortunately, is that the probability favors the former far more than the latter, especially when it comes to technological innovations. That is, while they aren't necessarily going to look like us, they're going to have very similar technology. Because technology likes being efficient, and thus it'll develop the same. All living things need food and shelter to survive. So they'll have houses. And their houses will more or less be like ours - efficient shelters designed for living quarters. Their food may not be like ours, but it's safe to assume they'll develop agricultural and/or husbandry (depending on their diet), because a constant and dependable source of food is great for developing species. And then you have the four basic machines! You kind of need them to develop things. It's highly unlikely that they won't have, for instance, four wheeled transports. Why? Because while it's one above the minimum number of wheels for a stable configuration, makes for great maneuverability. A six-wheeled vehicle is great for moving it a straight line, but it's unlikely that they wouldn't want efficient vehicles. It's at this point, I feel the need to stress something important. Just because you can imagine an alien race doing something different doesn't mean they will - the universe is a large place! You can construct very specific events and planets to have species develop weird stuff to the point where it looks like a Dr. Suess book, of course, but the going assumption should be efficiency, because technology loves being efficient. Step 2: Figure the base function for the product you want Let's take an instrument, it's a fairly complex item that can almost be guaranteed to be used by any species that makes use of verbal communication. There are some really fun and interesting variants that I'v seen, but if you want to break it down, then look at the simplest function - instruments make music. That means that what you want is a device which was explicitly designed to make music. Even something as odd of a race of insect might want instruments, if they developed complex speech. But your design perspective shouldn't be 'How can I adapt a flute to the insects', it should be 'What music would an insect listen to?'. Find a frequency range that makes sense, and work from there. Step 3: Form Follows Function Now, adapt an Earth object to the base function you want. Feel free to use as weird of an Earth object as you want, or make one up yourself, so long as you make sure its efficiently designed. That is, model it after something like a wind instrument, strings, or something of that sort. Do not come up with a brand new way of making music on your own! It's unlikely to be as good as the methods humans have come up with over the millenia. (And if it is, why are you writing fiction? Patent it and make a fortune!) Adjust as necessary for your aliens. Do they have four arms? Adjust. Do they lack opposable thumbs? Adjust. Do they all somehow suffer from Chromesthesia and thus would have a color palette on the instrument as well? ADJUST! This is also where your creativity comes into play and where get to reskin things. Once you've got the basics, adjust the trivial and non-important parts to give it some alien flair, if you feel like it. Step 4: Peer Review Same thing as last time. Once you've done all the legwork and research, (you've done research, right? Excellent!) then show it to someone who's well versed in sci-fi and see what they say. There's an off-chance that you might've hit the uncanny valley equivalent, so feedback is also important to adjust. And that's it! A simple 4-step process. [Answer] I think a way to achieve a generic processes to design alien commodities or items, is designing a list of generic questions we can answer, and having some considerations about each question to make it easier to answer. Ok now, let's try find the right questions: How did the species get the intelligence to produce tools? Evolution is not random at all, species develop what helps them to survive in a very slow process of random changes. It is possible that we achieve this intelligence level because we are designed to use tools like most primates. Smarter humans were more able to create better tools, and use it on more creative ways. Is a smart snake interested in using tools? How is their body prepared for using tools? Similar to the first point. We have hands, maybe some alien could use tentacles, sophisticated claws or a trunk like an elephant, without a specific body part to manipulate tools it is hard to think how they start to produce their things. Which necessities are they covering with those items? A big mistake here is thinking how is it going to work, for example, a chair for alien smart birds, instead you have to focus in which necessity we are covering with a chair, maybe a branch would be more appropriate for them. Having this in mind, we can work on it until we get something as advanced as the level of technology we want to achieve. Is art a thing? Art is something usual for us, we try to express our ideas or feelings in many ways, so we produce art. Is an alien with mental connection worried about how to express themself? If they don't need support for communication, probably they will not understand the idea of writing or painting, maybe they are more worried about disconnect themself in a kind of meditation perhaps. Where do they live? Which materials do they have? It is interesting to think on the materials, we have worked on stone, wood and metal for centuries. A crystal world would have different necessities and different approaches to the same problem. Imagine the possibilities if we had huge turtles living on our world or a kind of wood that is able to repair itself. Family, community and culture The way we interact, the way we talk, the way we love, even the way we make war, all the interactions have a repercussion on the way we think and design our things. --- Finally, why do we have to think aliens like animals or insects? Could plants be smart enough? What about robots or virtual minds ables to control matter? Maybe a mix? The space and imagination is big enough for everything. There is no a perfect process to write a book or build a world, take what helps you to create a more interesting world. [Answer] ## Adapt Human Technology and Solve Problems I would start with your aliens and a general human tech level equivalent. Your species will at least need to be able to create tools, so we know they are intelligent and have appendages with precise dexterity for creating tools. Example I am going to build a modern society with human sized dragons. They have wings and 4 legs, and when laying down to support their weight they can use their front limbs like arms. Now that I have a baseline, I can quickly decide which things will and will not exist in my world. TVs are till useful, so yep, their in. Same with computers, although I will need to change some things. They've got to be on the floor, and since typing with claws is dangerous, they will either clip their claws or use special gloves to type. Sofas are out, but I still need something with that function. Maybe a giant pillow in a basket on the floor. Now let's think about unique characteristic dragons have and how that would change their world. Flight, they can fly at around 35 MPH, so no need for cars except for the very wealthy. Trains would probably work for long distance travel. If I fly to work, I'll need a way to carry my laptop there, so there's a flying harness, which would basically be a backpack worn on your stomach. Don't want bugs to get in my eyes, so goggles are a must. And since I'm going to be covered in bug guts when I get to work, I either better carry a special towel or everywhere needs a cleaning station in the entrance. Ect. By going through and adapting what already exists and solving the specific issues their anatomy would have, I will end with a tech level that is both familiar, yet different. ]
[Question] [ When you have [foresight](https://5thsrd.org/spellcasting/spells/foresight/), it's guaranteed that confusion will be your epitaph (thumbs up to the one person who gets the joke). Basically, it only grants you advantage on actions, so you still can't automatically succeed in, say, rolling a d20 (not on the table, in the game), aka: you can't immediately know the precise outcome of an action. So, I thought I'd make a more science-y version. Foresight consists of a sensor array, a strong computer and an AI that calculates the probability distribution. I wanted to use probability distribution to make foresight more usable and realistic. In essence, you can see where a shot could land and make your evasive actions based on that. This also wards off Mistborn fans (If two precog warriors fight, then they'll get unusable probability distributions, so the powers "cancel" out each other). However, now I don't know what ~~King Crimson~~ foresight can effectively predict. What would be the most important factor for predicting what foresight can predict? [Answer] # Foresight can only predict predictable things. Yes, that's a tautology but I want to make a point - you can predict anything the module can calculate. For example, if you throw a die, then it can take into consideration force, angle, position, etc. and calculate what the most likely roll(s) would be. If you flip a coin, the module can also do a similar calculation based on physics - how much what is the speed with which the coin travels, what it's rotation, to derive an answer. However, if you're in the vicinity of something completely random that cannot be calculated, then the computer cannot derive any probability. Since the module also has to be fed data, that means that you get additional hurdles: * If something could not be measured, then it can't be calculated. In particular, if somebody is obscuring the view to a rolled die, there might not be enough data to derive a useful or correct prediction for where it lands. A gimmick die that, say, has 1, 2, 3, 4, 5, 1 on its sides (no 6, but an extra 1) might also produce an incorrect prediction. * Not all events can be predicted all the time. Perhaps you can calculate the exact trajectory of each lottery ball as they are being shuffled and you can derive the most likely combinations that will be drawn. However, you cannot do that a week in advance but only as the balls are being shuffled. And most of the time, you can't buy a lottery ticket as the lottery is being drawn, so you can't just win the money. OK, the latter can be somewhat alleviated by using statistics on past data. Perhaps, you can predict a reasonable amount of combinations for a lottery by analysing all past drawings and trying to derive a pattern of how the balls are being shuffled. Not in the draw but literally the shuffling - analyse the trajectories and you can know which ball is most likely to be drawn, assuming you know their positions before the shuffle. And if you also have data on how they are being put into the shuffling machine, then you just might get a good guess. However, even if you could simulate all of this perfectly (or well enough), then this foresight is still very vulnerable to disruptions - the janitor at the lottery studio might bump into the sack of balls which might throw off all your calculations. And since you can't see this, you can't know it, nor predict it. In a fight, the prediction module would be of some use but might also be misleading. It will be able to tell you where a strike would (likely) fall but only while the strike is coming. It's unlikely to be able to anticipate what your opponent is planning to do. Also the prediction might actually work against you - since the window for prediction is small, a smart opponent will feign an attack to get you to start to dodge in a direction and then redirect their blow to that location. You would be warned of where the real attack is going but it might be physically impossible to dodge away while already dodging. Again, past behaviour analysis could improve things. If you've fought or at least observed a person fight, the prediction software might be able to derive likely actions - e.g., attack from the left is usually followed by attack to the body. However, this again relies upon having sufficient and accurate past data to draw upon for prediction. An opponent could do something unexpected or change their style so an attack from the left is now followed by an attack to the head. Also, if there is no past data - you face somebody for the first time, there is no data to build a prediction - you mighty not even survive enough to be find out what a blow to the left might is followed with. Finally, probably the biggest factor is how much data and processing power the foresight module has. It might be able to predict the trajectories of all lottery balls but it might not have enough power to do it. It might not have good enough sensors to measure how a die was rolled or notice which pips show on the sides while it's in motion. It might have trouble with certain calculations because of the nature of the Math involved. The past analysis might be completely impossible due to lack of long term storage. Or even if there is long term storage, it might not be able to dedicate it to one thing only - for example, a particular person's fighting. [Answer] Lets take the Foresight-AI to the extreme Assumptions: * The AI is, like, super-smart * You computational power is handled by an arbitrarily big remote server farm * Sensors can scan three-dimensionally at micron-resolutions at range with sub-msec refresh rates At this level of scanners, humans become a joke to Foresight-AI. It is able to remotely scan and digitize the state of every neuron in a human's brain. Provided the AI has had enough training, it can then predict what the human will attempt to do faster than the human themselves know what they're going to do (including instinctual and twitch reactions). This means that a robot equipped with Foresight-AI would not be able to lose against a human in any sort of confrontation (including verbal/social). In fact, a sufficiently good AI would probably be able to create a Chinese-room approximation of any human it scans and completely predict it provided it knows the human's inputs (what they see, smell, etc.) The only way to combat such an AI would be with a machine which at it's core has some sort of random number source which steers it's actions. [Answer] Danger assessment comes to mind. In most fictional cases, foresight only triggers if something of importance will happen. A computer with a good enough sensor can calculate precisely where an arrow would land. But it will also calculate and find tons of other events that are not that important. Thus it would be very important to be able to filter out unimportant events. [Answer] Story time: A lad who was a year behind me in high school went on to cheat at Vegas. It was a team effort. The player at the roulette wheel had a clicker radio transmitter in his pocket. He would give two rapid clicks when the croupier spun the wheel, then 1 click when the double zero passed him, one click when it passed again. This gave them a time stamp and the speed of the wheel. One click when the ball passed, one click when it passed again gave timestamp and the speed of the ball. From this they could predict the landing of the ball with about 20% accuracy. The optimum number was passed back through a modified hearing aid. The casinos got wise and you couldn't place bets after the ball was in motion, but the team each made the price of a house over the course of a month. --- So becomes a module in FORESIGHT I. The first version of the system. One module tries to predict the stockmarket, but fails -- much like your superheroes, the actions of other players make the probability distributions too thin to matter. So look for situations where it would be reasonable, or at least possible to predict. A Human reactions module that can use multiple CCTV scans of a crowd to predict mob violence eruptions. Part of the conflict in the story comes from the small edge the system gives. E.g. It gives 15 minute mob violence warning 10% of the time, and gives about 4 false alarms for each real one. Give in an AI that can self program given a sufficient data set. E.g. Forecast earthquakes given a big enough pool of seismograph data. ]
[Question] [ I'm attempting to figure out the orbital physics of a system that has a habitable body that has intense periods of waxing and waning sunlight. I've come to the assumption that the best body for this to happen on would be the moon of a gas giant as I can use the gas giant to periodically shield the planet from star. This is not something I'm an expert in at all so hoping for help in figuring out what it would take for this scenario to be possible. If it's possible at all. So here's a lot of information on what type of system I'm thinking about, more details will be added as they come up. Goals for the moon : * Hemisphere A is habitable all the time, even if the environment gets harsh at times, the colonists have means to deal with temperatures up to 60-70 degrees Celsius. Majority of the primary colony and outliers are within exposed cave systems. * Atmosphere is breathable by humans * Gravity within 10% of earths, size doesn't matter much to me but should support cave systems * Developed basic life - mosses, fungus, primitive leafing things, insects, and amphibians. So the system in place has to have been stable enough to allow for life to develop. * It's not the only moon around the planet, but only one that has developed life and can sustain humans without creating habitats. Creating "Sunfall" * The moon should go through periods of time say 100-200 years where humans and other life can spread to 60-100% of the moon. Temperatures should reach points where no type of environmental suits are required. * The moon needs to go into Sunfall periods of 40-100 years where greater than 50% of the moon will be cooked. Sustained temperatures for long periods of time that will cause plant life to burn/die and would be lethal to humans exposed for more than 5-10min, either due to heat or radiation. * Sunfall isn't required to be constant, but last long enough and happen enough that it's not feasible for life to come back until Sunfalls stop, or their frequency drops to a certain point. Flexible with : * It doesn't 100% have to be a moon, I'm just not sure how you'd do this with a planet...would be incredibly awkward combination of things. * Environment can be extreme, but humans should be able to survive in the safe region without much in the way of equipment. * Colonists are used to weird days and living in cavern systems, they have clocks based on far-flung home planet so rotational and orbital periods don't matter as long as they work. * The type of star, or size and composition of the parent planet * Cooler periods can be longer, but I'd like to not have Sunfall last more than 1-2 generations of humans. What would a system look like to get phenomenon like "Sunfall" on a celestial body? If this doesn't seem possible that's also something I'm willing to accept and consider alternate possibilities giving similar impacts on the environment. [Answer] Off the top of my head, I feel like the easiest way to handle this is with a binary star system. Put your habitable planet in close orbit around a [dwarf star](https://en.wikipedia.org/wiki/Habitability_of_red_dwarf_systems). Planets close enough to a red dwarf to be habitable at all would almost certainly be tidally locked, which solves for the 'only one hemisphere is normally habitable' criteria in your question. Then have your dwarf star itself be in a highly elliptical orbit around a larger, brighter companion. I did [some calculations](http://www.calctool.org/CALC/phys/astronomy/planet_orbit) and if we assume a fairly standard dwarf star mass (.15 solar masses) with an earth-sized planet orbiting it a[t a distance that would allow liquid water](https://www.technologyreview.com/s/423341/white-dwarfs-habitable-zones-and-other-earths/) (.01 AU), the orbital period of the planet around the dwarf would be pretty close to 24 hours. This is handy because it also means that your planet is going to be rotating quickly enough to maintain a proper electromagnetic field. During most of the orbital period of the smaller star around the larger, your planet is only going to be getting energy from the dwarf, and only on the one hemisphere due to the tidal locking. You're also going to be getting a lot of tidal flexing on your planet which means plenty of tectonic activity, which will help keep things warmer than they might be otherwise. So. During most of the dwarf's orbit around the companion, your 'day' side will be temperate at the 'east' pole (the point directly facing the dwarf), fading towards an arctic climate as you get towards the edge of the illuminated surface of the eastern hemisphere. Your 'western' or 'night side' hemisphere will be mostly frozen. Think Antarctic winter. As the dwarf approaches its larger companion though, things will start warming up. You'll have a gradual period where the entire planet starts getting more and more energy from the larger companion and, because of the orbital period, you'll start to have something like a normal 24 day/night cycle increasing in intensity as the dwarf gets closer and closer to the brighter star. This will create your period of global habitability. At the point of closest approach, your planet will be getting SO much more energy from the bright companion that everybody has to return to the caves until you pass perigee and the dwarf starts its trek back outwards. This is your 'Sunfall' period where the combined intensity of both stars in close proximity creates too much heat for comfort on the surface. Then you have a second 'season' of global habitability as things gradually cool off, but the planet is still getting daylight from the large companion throughout its orbit. After a while the dwarf passes far enough from the companion that the energy becomes insignificant again and you have the long cold winter until sunfall comes again. The more elliptical the orbit is, the longer you'll spend in the 'winter' phase where your planet is only relying on the dwarf, and the shorter your habitable and Sunfall phases will be. Generating the kind of timeframe specified would require an orbital period of the dwarf around the larger star of around 400 years, which requires a semi-major axis of about 60 AU. For comparison Pluto's semi-major axis around the sun is 40 AU. The math of exactly how long the Sunfall period would be in this case is a bit beyond my mathematical capacity so I'm hoping someone else will fill in the gaps on that, but with an elliptical enough orbit the 20-40 years you specified should be easily possible. [Answer] Variable star. Your moon is just a humble moon, doing moonly things. Your star, however, is moody. It has dim and bright cycles. It is a variable star. [Periodic measurements of variable stars using AASO data](http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=2010JRASC.104..158F&db_key=AST&page_ind=0&data_type=GIF&type=SCREEN_VIEW&classic=YES) > > Variable stars are stars that vary in brightness over time. This can > be caused by a variety of effects.... There are also intrinsic > variable stars that are caused by changes within the star itself. An > example of this is a star that is periodically collapsing. As it > collapses the pressure in temperature inside the star increase, > causing more light to be emitted. The increasing pressure then > causes the star to expand outwards, restarting a cycle. > > > There have not been accurate astronomical observations for long enough to determine if there really are any stars that cycle with the long period you want. But stars can cycle and making the Sunfall happen because of the star itself would be a fine and plausible thing. If it is the star that is up to these games, I could imagine that the gas giant would also change in appearance from hot to cold cycle. Its atmosphere would expand as it heated up, for sure. More energy in the atmosphere might also cause electrical effects. I do not think those things would affect a moon in orbit, but you could definitely see them happening from the vantage point of the moon. ]
[Question] [ The Ressurectinator is a handy machine than can bring back people from death. Unlike the virgin Lord of Light, the chad Ressurectinator does that without human sacrifice and/or permanent scars. You only need the person's brainscan. Everyone has one, it's constantly updated and nothing can destroy it. There is one weakness to the machine, however. The person, it brings back, would feel the pain they felt when dying, WITHOUT the dopamine/adrenaline that coursed through their body. This is weird, since the machine brings back demi-humans and dragons as well, both of whom have much stronger senses, and thus, a stronger sense of pain. It doesn't helps that most of them sustain horrible injuries before dying (broken wings, throat sliced up to the chin, 3rd degree burns). The machine is owned by the good guys and isn't designed to make a profit. Logically, phantom pain would be used as a deterrent, so the good guys finish the war with declaring bankruptcy. However, dying IS painful and HORRIFYING. The effects of the Ressurectinator are guaranteed to increase the number of soldiers with PTSD, which is even worse than respawn abuse. So, why would the machine do this? Anything I didn't touch upon about the machine or the good guys (religion, morality, evil professor) cannot be used in the answer. [Answer] The machine doesn't cause it, the brain does Phantom pain is the sensation of a lost limb. It's a bit weird, given that there's no limb to give the pain and no nerves, so there's only one explanation - its psychosomatic. The pain is in the mind, it's some part of the brain which hasn't acknowledged the missing arm. And, as a plus, it's not well understood. (Why is that a plus? It means we don't have to use excessive handwavium because we're not contradicting established fact.) When a person dies, there body gives out, and then the electric synapses it the brain does. (Not it all case, but most. This won't happen if the entire head goes at once.) That means that the brain has acknowledged, on some level, that the body has been destroyed. Thus, when the body is resurrected, there's still a part of the brain that 'remembers' the destroyed body, and attempts to overlay it onto the new body when the person uses it. For instance, if you suffered a shot to the heart and died from it, whenever a message involving the heart is sent to the brain, some subconscious part of it is triggered, says 'that's funny, we don't have a heart because it got shot', and then the message of 'the heart got shot' gets sent to person. It makes sense - there's no such thing as a free lunch. [Answer] # The Cost of Verisimilitude when Accounting for Ineffable Variables ### You aren't You The problem with transporter technology is that the person who appears at the destination is not the person who stepped into the transporter at the origin: they are a duplicate, and the original is gone forever. The same problem would ostensibly exist with the Ressurectinator: it merely inserts the brainscan of the patient into a new body. The person who died isn't the same person who came back, just an exact duplicate. But that begs the question: what has been lost in this process? The science of the Ressurectinator can account for all physical variables, down to subatomic particles, so the only difference must lie in something outside of physical variables. Something ineffable; scientists could just refer to this as "the soul" for quick reference. ### Why aren't You Yourself? Keeping the brain scans updated is easy: the Ressurectinator has a read-only quantum-entangled pattern of the patient's mind which is updated in real-time as they go about their day. One visit to the Ressurectinator is all it takes to get the process started. Early experiments involved resurrecting someone using a 1-minute "tail" of their realtime scan, allowing them to be brought back without the traumatic memory of death itself. But this raised ethical concerns: if someone is being resurrected with part of their memories missing, then are they truly themselves? Those performing the resurrection have essentially edited out an inconvenient memory from their patient, and brought back a mere duplicate. The person who originally stepped into the Ressurectinator to get their brain scanned is dead forever. ## If it Stings, that means It's Working The solution was to use the final brain scan; the last moment when the scan stopped updating and became static. That is the truest possible copy. The variable has stopped varying, and become a constant. When this scan is used, the patient is resurrected with all of their memories intact, including those of dying. The downside is that the pain they felt at that moment is now persistent. Some scientists might believe this is the equivalent of the Soul itself being scarred by the experience, and evidence that using the "true" final scan allows the Soul itself to be brought back. This is not merely a duplicate, but undeniably the same person who died. Other scientists might believe that this is just a side effect of using the brain scan after it has stopped updating--the sensations experienced at the time of death are now "hard coded" into the scan itself. The unfortunate fact is that no one knows for certain. But regardless, there is agreement on one fact: a person resurrected with these phantom pains is the truest possible resurrection. Anything else is just a copy. [Answer] Your new body is an approximation of your old body. You are more than just a brain scan, your mind only works when integrated into YOUR body. If you throw a dead body into the machine it can perfectly revive all the parts that are still in tact, but the missing and damaged bits are a simulation of what that part should look like. The machine guesses what cellular structures should be there, but things tend to come out slightly extruded or misaligned. This approximation is good enough for muscles, bones, and other tissues so you do not appear scared, but the exact course your nerves take through your body are much more precise and unpredictable; so, they tend to get pinched or malformed in recreation process. [Answer] Soul. That could case quite the uproar in the scientific community. You have empirical proof that with the same mind using the same body it does't work the same. The process is repeatable and can be validated by technicians in other facilities. The model of what constitutes a human is thus insufficient and must be further developed. That's a Pandora's box with plenty plot bunnies to write a fun story. ]
[Question] [ I have a world designed called Ser. I want to place tectonic plates so that they can explain how the current landmasses formed. Below shows the 6 major continents of the world. As continents are commonly defined by their tectonic plates, I want this to be a guideline to how to determine where the tectonic plates should be. [![The 6 major continents](https://i.stack.imgur.com/ScVre.png)](https://i.stack.imgur.com/ScVre.png) Below shows how the landmasses have fit together in the past. The color brown indicates regions of mountain ranges. The colors on the shorelines represent how other landmass fit together during the last supercontinent. [![How the landmasses fit together in the past.](https://i.stack.imgur.com/rKBDQ.png)](https://i.stack.imgur.com/rKBDQ.png) Based on these two images, I want to decide where tectonic plates and their movement could have split the landmasses apart the way they are currently represented. My previous research has helped me determine that divergent boundaries are usually between landmasses they are separating (forming mid-ocean ridges), and convergent boundaries are commonly at the location of mountain ranges. Although, these facts do not have to be a restriction. Constraints: I don't want to change the continent division. I don't want to change the locations of mountain ranges. I also don't want to alter the landmasses at all. *Good answers will provide tips and/or resources that will help me decide where my tectonic plates should be. Please be descriptive and explain where plate boundaries should* be and where they should not be, based on the data in these pictures. EDIT:** The planet depicted is an Earth-sized planet, and the landmasses shown in the images are all of the landmasses of the planet. [Answer] ## You have a few problems 1. Starting on the left, purple, you can't have a land mass between two places that were once joined,otherwise if you wind time back they can't join up because there is a land mass in the way. 2. Pale blue, you can't form spikes like that,not as a plate to plate break. You can't have a sharp V shaped spreading center, crust breaks in 120 degree angles. The only way to get a narrow seaway is to have a spreading center in the center of it. and the only way to get a large acute peninsula is a subduction zone uplift, or multiple sequential spreading events in close proximity. 3. You have way to many scattered large islands, if a landmass moved through someplace there can't be a bunch of large islands where it moved, it would have scooped them up. Islands are either so small they should barely show up on the map or they are chunks of continental crust, which means they need a whole plate pushing them along, they can't move over other plates moving other islands. You can have a few but not a whole mess of them and definitely not in a shotgun scattering, you can get a chain of islands on a subduction zone but that s what shape they will take a subduction arc (Alaska or Japan), or two subduction arcs coming from two directions for earth (Oceania). And you will not have many between two landmass boundaries that were once joined, there is no way to get them there. 4. On the right the purple spiral is a mess, you can't have a divergent boundary between two mountain ranges, a spreading center will not form on thickened crust, spreading centers form where the crust is weak and thin, they are literally breaks in the crust and a material is not going to break at its strongest point. 5. Looking at the map overall you also can't have nothing but divergent boundaries, every sea you have is bordered by land masses that were joined, that can't happen unless your planet is actually getting bigger. crustal material has to go somewhere, if it is being forming in one place it has to be getting subducted somewhere else an the same axis, otherwise the diameter of the planet along that axis is getting bigger. You can get a away with some minor ones because your looking a two dimensional representation of a spherical surface but they need to be more hinge like (dead ended) so rotation is happening. I considered running a continent to continent convergent boundary down hte middle of your central continent but it is too small to support that, one of the oceanic plates would just give way and start subducting, the Himalaya only exist because Asia is huge and India is small yet close to its spreading center. I have done my best with your map while trying to change as little as possible. Spreading centers are marked in red and subductions zones marked in green. If two places can't be areas that were once joined I have erased the matching colors. Islands that I just couldn't justify no matter how much a stretched I just erased. I added a mountain range near the yellow coastline because subduction zones create mountain ranges, and putting the subduction zone there disrupted less of the map than anywhere else. I have just ignored your first image because it makes no sense, they look like political borders not tectonic ones. [![enter image description here](https://i.stack.imgur.com/eVL5A.png)](https://i.stack.imgur.com/eVL5A.png) Really you would be better off starting over from scratch, it will look a lot more convincing. Or at least you have to do some serious editing of your map to make something possible. You have too much land in the mid & low latitudes and too many random islands.ideally you could even take a bug chunk out of a continent to open up some room for things to move. The best way to build a map is to start with rough idea of what you want and work progressively towards it instead of taking a finished map and asking how to fix it (and that is what you are asking whether you intend to or not). I know you don't want to change anything but you just can't make something believable from what you have without changing it. Sometimes the answer is "you can't get there from here". You can't add in techtonics after the fact, techtonics are what creates landform. The quick and dirty way to map spreading centers is just make a line in the center of the ocean that roughly matches the coastline wherever you have two coastlines that match. Spreading centers are not always centered but they most often are. You need large subduction zones to move them away from center. if you have two parallel spreading centers you either need a subduction zone between them or one on each side, again crustal material has to go somewhere. Mountains are formed by convergent plate boundaries, sometimes they are old plate boundaries but if mountains are near the coast that is usually due to an active subduction zone, hence why I put your subduction zones near existing mountains whenever possible. ]
[Question] [ In my [previous question](https://worldbuilding.stackexchange.com/questions/154392/to-handwave-or-not-to-handwave) a guy called Thorne pointed out that I could make a high-velocity coilgun without using a barrel of enormous length by taking a page out of the LHC's book and using a circular coilgun, allowing the projectile to run several times around the track. That particular question wasn't really about coilguns, though, and I had another [previous question](https://worldbuilding.stackexchange.com/questions/154298/how-powerful-a-starship-coilgun-can-we-make?noredirect=1#comment485229_154298) that was. In my coilgun question, the most reasonable answer suggested that a coilgun with a 100 meter-long barrel might, just might be able to get a fairly small projectile up to about 30 km/s, but almost certainly couldn't do the same with fairly massive one. So, does the answer change if I'm using a circular track to accelerate the shot? Let's assume the track I have to work with is about 300m in diameter, and once again my goal is to get a 1000kg projectile up to about 30 km/s. I suspect that the mass of the projectile will once again be a problem, though; and I suspect that the design of the accelerator will probably lend itself more to a constant stream of ball-bearing sized iron shot. EDIT: To clarify, the idea behind the circular coilgun is that a projectile can run around the track more than once before it is fired. The barrel length of the gun is thus effectively infinite (or rather, unlimited), it can be however long it needs to be to get the projectile(s) up to speed. I just don't know whether this makes it practical or not. And on a related note, what about use of an actual ring-shaped particle accelerator as a weapon? Devices like the LHC are kilometers in diameter, and while they can get their particles up to nearly the speed of light (from what I've heard), the actual destructive power of the beam isn't that great. I don't need a particle stream anywhere near that fast, as long as I can dump enough mass into the beam for its effect on the target to be worthwhile. Is a 300m diameter ring anywhere near enough to be useful? Can such an accelerator be built as a weapon? Maybe that's why the Enterprise has a circular saucer section... [Answer] The answer given by mcRobusta accounts very well for the circular accelerator. The formula is indeed $F=\frac{m v^2}{r}$. But to compare to the linear case, consider a linear gun with barrel length $d=2 r$. At constant acceleration the exit velocity is $\sqrt{2 d a}$. That is, to get a velocity of $v$ you need a force as follows. $$ F = m \frac{v^2}{2d}= m\frac{v^2}{4r} $$ That is, to keep your mass going round the ring you need to accelerate it 4 times as hard as to get it to the same speed in one diameter. Which isn't that strange since you are in fact flinging the mass back and forth at its maximum speed, meaning you must go from full speed "left" to stopped in one radius, then back to full speed "right" in one radius back. So if you are looking to use smaller force, the linear gun is best by a factor of 4. Edit: To respond to the comment. The ring needs to accelerate the mass with a force $F=\frac{m v^2}{r}$ all of the time until it is released, just to keep it in the ring at speed. In addition, you need to apply the force that gets it up to that speed. The only advantage of the ring is the getting-up-to-speed acceleration can be smaller. And that is only an advantage if you have some relatively cheap (from a force and energy point of view) way of having the mass keep turning in the ring. And that's a problem I see no solution for. Spinning a mass with electromagnetism, for example, will use just as much energy to make it move in a ring as along a straight line. Additional edit: The failure modes of a ring of this nature will be spectacular. The energy in the electromagnets will very likely be many times the energy in the mass. Good possibility you would see the ring turn to plasma if you got any kind of failure. And the mass would exit in some random direction. Should my military superiors place me on duty on such a device, sabotage and desertion would start to look like pretty good career moves. Even further edit: I just noticed mcRobusta's paragraph about the electromagnetic ring not communicating the force to the ship. [Isaac Newton is not fooled!](https://en.wikipedia.org/wiki/Lorentz_force#Force_on_a_current-carrying_wire) The force you apply to the projectile using electromagnetism is precisely equaled by the force the ship feels. This is [Newton's Third Law.](https://en.wikipedia.org/wiki/Newton%27s_laws_of_motion#Newton's_third_law) If you push the mass by whatever means, the mass pushes back. Electromagnetic propulsion is not a free lunch in this regard. That, by the way, means the ring is going to apply a torque to the ship as the mass spins up. Probably that is inconvenient to navigation even if the structure of the ship can stand up to the forces. [Answer] Our friend Isaac Newton can help us here with his equation of circular motion: # $F = \frac{mv^2}{r}$ where F is the force produced, m is your object mass, v is your object's linear velocity, and r is the radius of motion. As you can see, it's the speed you want to reach that is going to have more of an impact than your mass (which, by the way, is still a problem). Based on your numbers, you'll be subjecting your accelerator to 6 billion Newtons of force. This will likely cause it to break into tiny pieces. By the way, 30km/s is Mach 88 (88 times the speed of sound). This rotary force is enough to fling New York City into space- you must have some interesting needs. Running your cannonball at Mach 1 (340 metres per second) will still put a big hole into whatever you fire it at. You'll put 771,000 Newtons of force onto your accelerator, which at a big enough scale it should be able to handle. On a final, more interesting note, the velocity of an object in a circular path acts at a tangent to the circle, but the acceleration (and thus the force) acts towards the circle's centre. As the direction of velocity is constantly changing in a circle, any object in circular motion is accelerating with this force. Something to consider in your designs. EDIT: Have you considered modelling the projectile as a point charge in a magnetic field, and accelerating it radially? My maths may need some touching up here, but using the equations for magnetic flux density we can see: $F = BQV = \frac{mv^2}{r} $ where B is the magnetic field strength, Q is the value of the point charge passing through the field and V is this charge's velocity. Using this, we then get: $ BQ = \frac{mv}{r} $ Plugging your numbers back in, it turns out that the product of our magnetic field strength and charge of the particle needs be 200,000 Tesla Coulombs. Teslas are harder to increase than Coulombs due to their exponential nature, so lets keep those low. [We can already produce up to 45 Teslas, so let's say we can produce 50 on your spacecraft](https://nationalmaglab.org/about/maglab-dictionary/tesla). This means your projectile needs a charge of 4,000 Coulombs (which is still a lot), but assuming you keep it in a vacuum and it's perfectly spherical, you can use [Gauss' Laws](http://physics.bu.edu/~duffy/semester2/c04_spherical.html) to calculate the current needed to be held in the projectile and the distance it needs to be from its enclosing magnets to reach this exit velocity in a certain time. Without number crunching myself, it doesn't look so bad. Plus, with magnetic confinement the force of your projectile is meaningless as it's not actually producing a net force on any surface connected to your ship. EDIT II: Electric Boogaloo As suggested by @Efialtes in the comments below, this system would require a ridiculous amount of energy. By substituting in $ E\_K = \frac{1}{2}mv^2 $, we can calculate the projectile's energy is 0.45 TeraJoules. I cannot begin to quantify how huge this is. Further, the field would have to be able to shift one million kilograms every five seconds to produce this power. Using equations for electrical energy (and assuming the device is 100% efficient), running this device for ten seconds would require a terawatt of juice. If you prefer, we can assume this device has an internal resistance of 10,000 Ohms (which would be very low). I can then tell you this would need a continuous supply of 2.08 MegaAmps. [It takes one MegaAmp to fuse together atomic particles in a superheated plasma](https://aip.scitation.org/doi/10.1063/1.1352595), so I really don't envy anyone tasked with designing something like this. [Answer] Sorry, but the requirements in energy would be so large as to prohibit a coilgun. Plus, as other people have mentioned already, there is the problem of bracing said gun. A particle accelerator, on the other hand, might work. They require much less power, have a much higher "muzzle velocity", and have a longer range. That being said, the amount of power involved would still be enough to instantly destroy the ship if the Accelerator were to be damaged. Instead of messing with energy weapons, I suggest just using a Centripetal Cannon. They are much cheaper, their range is similar to that of a coilgun, and the energy involved in firing is small enough that the failure mode would be "overloaded plasma conduits" instead of "instant death by being turned into plasma". Overall, it is a much better weapons system. ]
[Question] [ Closed. This question is [opinion-based](/help/closed-questions). It is not currently accepting answers. --- Want to improve this question? Update the question so it can be answered with facts and citations by [editing this post](/posts/153441/edit). Closed 4 years ago. [Improve this question](/posts/153441/edit) Technology in 2019 has many ways of augmenting the human body, for example: hearing aids, pacemakers, artificial hips, breast implants, artificial spine discs, coronary stents and even artificial eye lenses. In addition to that there are many different kinds of prosthetics, even thought controlled. Presumably the next big step will be all artificial organs, combined with advanced prosthetics, and humanity will enter a cybernetic era. Assuming that at the peak of cybernetics era, the nanotechnology is perfected to the point where humans don't need surgeries that replace human organs and body parts. Instead, the nano robots that are always present in the blood stream instantly repair any damage to all organs and body parts and augment the human body, greatly increasing all capabilities. Question: What would be the next step after nanotechnology, and why? (for example: could nano robots be replaced with some kind of DNA programs that are immune to EMP weapons in the wars of the future?) [Answer] # "Ship of Theseus" brain replacement (The details are [here](https://en.wikipedia.org/wiki/Ship_of_Theseus)). If you have nanotechnology and picotechnology, you can work at a scale below glial cells and neurons. This allows to record and "decode" the operation of every single neuron, one a a time. Each new "nanoneuron" would interface with either existing biological neurons or other nanoneurons. A single neuron's firing "rules" are quite straightforward (we know this from experiments on organisms like Planaria and freshwater snails). Our problem now is that complexity scales up so quickly that it's impossible to decode any significant neural circuit from above its scale. Nanoneural machines would not have this problem, and they could replace the brain one neuron at a time, leaving it working exactly as before. But now the brain's state can be analyzed, transmitted, and saved. Also, defective or damaged neurons can now be replaced from backups. New neurons can be added, once the energy budget limit that dictates brain size has been removed. Once all neurons are actually nanomachines, their "clock" might safely be increased. With a nanonic brain and a suitable body, man can now become immortal - as well as perhaps increasing his "natural" intelligence and controlling his body. Darker possibilities include that of analyzing a brain state in search of the roots of some given convictions, beliefs, and loyalties - either to verify they're there, ensure they won't change, or ensure the opposite. [Answer] # Picotech and Femtotech If you define the technologies available by the scale of engineering that is being supported, then of course the next stage involves [Picotech](https://www.orionsarm.com/eg-article/5356fad54ad52): > > technology or set of technologies that rearranges matter on the picoscale with something analogous to nanotechnology's scope and precision. It would supposedly allow not only precision arrangement of atoms but even arrangement of their internal states, leading not only to enhanced control over natural chemical reactions but to the creation of entirely novel atoms and molecules, including some stable and useful forms of exotic matter. > > > And after that of course would be [Femtotech](https://www.orionsarm.com/eg-article/5356fa37e30fe): > > a technology or set of technologies that rearranges matter on the femtoscale, with something analogous to nanotechnology's scope and precision. Femtotech would supposedly allow precision arrangement of the elementary particles that make up atoms. This would supposedly allow such things as transmutation of elements without the use of massive facilities or the release of radiation, the creation of various kinds of exotic stable or metastable elements and other fantastic effects. > > > [Answer] Task Specific Incarnations As @WorldPeace suggests, brain replacement is the ultimate physical upgrade; allowing the consciousness to move from body to body and through the discipline of keeping backups and regular body maintenance, escaping death entirely. Once that is achieved, although it will still be nice to have nanites onboard for impromptu repairs, the next big thing will be customization... * Need superior vision for your detail-oriented job, replace your human-norm optics with our new EagleEye 3000 occular replacements. Unlike the simple eye-replacements of the past, this new offering replaces your entire host and includes increased neurological tissue dedicated to interpreting your new higher resolution world view in real time and massive amounts of storage so that you never forget the details. * Going on a more sensual vacation, why not ride in a new host with ten times the normal pleasure receptors. Every nerve in your new body is optimized for your enjoyment. * Joining the latest Martian archaeological team, only a fool would leave Earth in less than a BioDome III fully sealed and self sufficient host. Models available for week-long, month-long and even year-long adventures between replenishment breaks. Fully radiation and vacuum resistant or your money back. [Answer] That’s a tough question... especially because some of them are questioning the human nature at its core. But as can be seen ..the human strives for any enhancement possible to perfect itself. At some point it might be possible to replicate our brain to such a degree that existence itself becomes a question mark if it really is just like a picture but just more complicated. The body at that point would become somewhat unimportant...if a clone can persist and individuality is more seen as a process of the development of that picture through time and each iteration and change made. At that point humans might give their bodies any form they can think of and what is doable. Death would also be not a question anymore. Bodies might not be reproduced naturally anymore but be hulls that you can put your brains into. At that moment though, humanity ceased to exist. Dark enough :0 ? [Answer] Following the theoretical technological roadmap given in Kurzweil’s ‘The Singularity is Near’, you are not far off from transcending biology entirely, assuming that parallel technology has developed that can reproduce and then exceed the computational power of the human brain. ]
[Question] [ I wanna build a habitable desertworld which is a gas giant moon. The desired and already semi-fixed parameters are: * mass between 0.4 and 0.25 Earth-masses * only 10 to 30 percent global ocean cover, water is mostly near the poles * orbits a 13,1 jupiter-mass warm superjovian * extensive vulcanism and some plate tectonics * global average temperature between 40 C and 45 C, just shy of a runaway greenhouse effect * only one atmospheric circulation cell due to slow rotation (the moon is tidally locked) * sun is an old F-type with only a few hundred million years left on the main sequence For story purposes I want the poles to be separated by a huge, scorching, equatorial desert. I don't want any rainforest or even savanna near the equator. Hot-semi arid (Koepen climate class BSh) bands on the equator would be the most I'd be willing to accept, oasis of it would even be welcome. [Messing strongly with axial tilt is not an option, sice I don't want a pole-equator climate switch or exteme seasons.](https://worldbuilding.stackexchange.com/a/145947/58321) Will my setup already deliver what I want? If not, what could I tweak? [Answer] If you don't want rainforest around the equator, you have to get rid of the rain. How? Easy! Take away the ocean! If the belt comprised between the tropics and the equator is above the sea level, there will be no ocean from which water can evaporate and then condense into rain. Rain will only happen around those areas where the ocean is present and atmospheric circulation can bring the humidity generated above them. Removing rain from the equator, combined with the strong illumination, will necessarily turn that region into a scorching desert, as you desire. [Answer] The gravel sea, it will actually be largely composed of much larger rocks but, if the equatorial/tropical zone is largely composed of plains of boulders and gravel interspersed with remnant hard rock peaks it can rain as much as it likes at any latitude but the water table will be inaccessibly low for vegetation to grow. This is a self reinforcing cycle as lack of vegetation cover increases the [erodibility](https://en.wikipedia.org/wiki/Erodability) of finer rock particles. This does require relatively consistent wind conditions to move fine dust continually away from the equatorial latitudes but that makes sense in a tidal locked situation. Water will occasionally be available in places: * where larger than usual rocks create openings that extend down to the water table, this water will probably be pretty brackish or possibly even actively saline. * where pockets of finer sediment support [capillary migration](https://en.wikipedia.org/wiki/Capillary_action) of water from depth to the surface, such water may be quite fresh, resembling a mineral spring or quite nasty depending on the sediments in question. * where a layer of fine sediment at depth terminates and [gravitational head](https://en.wikipedia.org/wiki/Hydraulic_head) creates springs, this water will probably be quite fresh. But these will support only isolated pockets of life in an otherwise inhospitable, and quite impassable terrain, the lighter the colour of the rocks the more of a baking desert the area becomes. [Answer] Salt pan of death, there once was an equatorial ocean on your moon but after the gas giant captured another large moon in a resonant orbit the habitable moon got a lot warmer. There are several other mechanisms that could also raise the temperature but the new resonant orbit is needed because crustal flexing makes the moon more oblate, the once reasonably deep ocean is now very shallow, the whole region resembles the [Salar de Uyuni](https://en.wikipedia.org/wiki/Salar_de_Uyuni) salt flats in Bolivia as seen below. The area has plenty of water at or just below the surface of an unstable shifting salt crust some of that water is extremely, lethally, deep. There are mechanisms to form occasional fresh water springs in isolated parts of the pan mainly due to gravel deposits near the edges. The former islands of the equatorial sea are now mountain peaks that may be vegetated, the reflected light from the pan will keep effective temperatures higher than most plants deal with well but desert species should thrive. [![](https://i.stack.imgur.com/HIR16.jpg)](https://i.stack.imgur.com/HIR16.jpg) Bolivia's Salar de Uyuni, 12,000 square kilometres of shifting salt and hyper saline lake water. ]
[Question] [ Superhumans in my setting work based on advanced technology (but not clarketech; no violations of physical laws, no FTL). My question is, how can a superhuman direct electricity? From my understanding of electricity, it moves in the easiest path it can take. Air, for instance, retards the motion of electricity until the energy level reaches lightning level. But I need electrokinetics to be able to move electricity at their command. No psychic powers exist, but nanotech and neurological modification are two paths I can see possibilities in. [Answer] Set things up to be a 2 phase deployment. Since you are open to Nanotech and Neurological mods, have it work like this: Nano bots, controlled by neurological signals, produce a long, thin extension from the controllers hand. These nanites are going to have a conductive shell for the electricity to follow. They may or may not have some sort of filament trailing behind them. They launch and make contact to the target, creating a path for the electricity. If need be, a bit of extra effort may go into creating a path for the electricity to get to the ground. Then, electricity, from an array of supercapacitors, discharges along the path created by the nanites. The amount of current will likely vaporize the physical path as the discharge happens, but that should be okay as the path through the air should already be established for a secondary blast, kind of like lightening following the same path on a secondary flash. You are going to have a fairly short range, and burning up the mass of nanites is going to probably going to give you a limited amount of discharges. Also, your superhero costume should probably have really thick rubber souls and should not be worn in the rain. [Answer] If you are looking for someone who can just direct an electrical jolt to a specific location, [electrolaser](https://en.wikipedia.org/wiki/Electrolaser) tech is probably the right starting point. Your super human could project a very brief but very powerful laser to ionize the air. This then acts as a conductor for your blast of electricity. It will not give as much control as Paul TIKI's nanobot idea for doing things like arcing your lightning around things, but it will have a much better range, and you won't have to wait for your nanoswarm to get into place before firing. At current tech levels, such weapons are rather bulky, but future tech may be able to miniaturize this to some sort of subdermal implant, gauntlet, or maybe even a very specifically bio-engineered organ; though, the last option is a bit handwavy IMO. ]
[Question] [ Earth's atmosphere, as you probably know, is divided into five layers - the troposphere, stratosphere, mesosphere, thermosphere and exosphere. <https://en.wikipedia.org/wiki/Atmosphere_of_Earth#Stratification> How can I determine plausible altitudes for the boundaries of these layers for my Earth-like planet's atmosphere? I have already figured out the atmosphere's composition, pressure\, density\, and escape velocity, and I know other possibly relevant things about the planet such as mass, radius, gravity, density, surface temperature, albedo, axial tilt, orbit etc. Are these values necessary? If so, are there any I need and don't have? Also, a couple clarifications: 1. I'm not necessarily looking for an empirical, universal method to precisely determine the exact figures, I just need a way to give me reasonable results, 2. I know that something like layers of the atmosphere might seem insignificant for worldbuilding, but I am interested in knowing this for my planet, and so I'd rather not just handwave it entirely. \at any altitude; I have a calculator for that. EDIT: As per Morris The Cat's request, I've shared the values regarding the planet and atmosphere. Here they are: Mass – 1.2x Earth Radius – 1.17x Earth Gravity – 0.88x Earth Density – 0.75x Earth Semi-major axis – 0.92 AU Eccentricity – 1.8x Earth Periapsis – 0.89 AU Apoapsis – 0.95 AU Year – 0.8x Earth, 294 Earth days Orbital velocity – 1.14x Earth Axial tilt – 1.17x Earth Albedo – 1.22x Earth Escape velocity – 1.01x Earth Atmosphere – 71.9% N, 25% O2, 1.95% Ar, 1.1% CO2, 0.05% trace gases Atm. pressure @ sea level – 1.45 atm Air density @ sea level – 1.7x Earth Specifically I've compared them to Earth's corresponding values which I thought were most fit for what the comment suggested. [Answer] The five primary layers of the atmosphere are, with increasing, altitude, the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. The corresponding boundaries are the tropopause, stratopause, mesopause, and thermopause. Here's how those boundaries are defined: [Tropopause](https://en.wikipedia.org/wiki/Tropopause): The [lapse rate](https://en.wikipedia.org/wiki/Lapse_rate) $\Gamma=-\frac{dT}{dz}$, the change in temperature with height, goes from positive in the troposphere to negative in the stratosphere, being zero at the tropopause. * [Stratopause](https://en.wikipedia.org/wiki/Stratopause): Temperature in the stratosphere increases with increasing altitude; the stratopause is where a temperature maximum is reached once you exit the troposphere. * [Mesopause](https://en.wikipedia.org/wiki/Mesopause): Temperature in the mesosphere decreases with increasing altitude; the mesopause is where a temperature minimum is reached once you exit the stratosphere. * [Thermopause](https://en.wikipedia.org/wiki/Thermopause): The thermopause is located at the point where the [Knudsen number](https://en.wikipedia.org/wiki/Knudsen_number) $\text{Kn}(z)$ [is about equal to one](https://en.wikipedia.org/wiki/Exosphere#Lower_boundary). Essentially, to determine most of these boundaries, you need to determine a temperature profile for the atmosphere, and from there calculate $T(z)$, $\Gamma(z)$, etc. This is typically not exactly trivial. [Answer] Are you straining at a gnat? It's tough not treating questions like this as POB. We have one datapoint to work with: Earth. Yes, technically we have the other planets in our solar system, but they're not life-bearing. Expressing a method of predictably calculating details like this when you only have one datapoint to work with is like trying to balance a platform on a single point: it can be done in many ways and they're all correct. Thus: POB. So, why am I answering your question? Two-fold: (a) I'd like to point out that the level of detail you're asking for (what is a plausible altitude...?) is a detail that is, without proof, very unlikely to be needed in your story. Frankly, the five layers aren't defined by exact altitudes (but rather a range of altitudes) here on Earth. And what that altitude is above Denver is different compared to Death Valley, CA and the Tibetan Plateau. My point is, does your story need any more detail than to simply use the atmospheric stratification names? (b) Occam's Razor suggests that, all things being equal, the simplest answer is usually correct. I therefore invite you to consider a simple truth: those five layers can be as easily defined by ranges of percent-of-atmospheric-altitude as they can actual altitude. Thus, using our single datapoint as a model: * Exosphere: 700 to 10,000 km (440 to 6,200 miles) or 7%-100% * Thermosphere: 80 to 700 km (50 to 440 miles)[15] or 0.8%-7% * Mesosphere: 50 to 80 km (31 to 50 miles) or 0.5%-0.8% * Stratosphere: 12 to 50 km (7 to 31 miles) or 0.1%-0.5% * Troposphere: 0 to 12 km (0 to 7 miles)[16] or 0%-0.1% Now that we have conversions to percentages, all you need to do is take your planetary statistics, determine the outermost altitude of your planet's exosphere, and apply the percentages. Would there be variances due to things like density? Yes — but I postulate that for the purposes of your story any such analysis is way beyond the level of detail required for a believable story. In other words. I don't think you need to strain at a gnat. ]
[Question] [ An Earth analog had been modified by an advanced species to have saltwater seas in an interconnected grid across the planet's surface. The planet has no true oceans and only the large grid network of saltwater seas. Each sea is approximately 80 miles in width and varies in depth from 1 to 2 miles at the deepest. What would the effects on climate be? Would it have an even temperate climate since water can move across the globe or harsh due to lack of oceans? Edit: Imagine they follow the planet's lines of latitude and longitude. [Answer] * Those oceans are extremely deep for their size. Any mechanism to prevent them from [silting](https://en.wikipedia.org/wiki/Siltation) up over geological ages? * Small seas mean you cannot have very large rivers, or large [watersheds](https://en.wikipedia.org/wiki/Drainage_divide) for those rivers. * Having substantial bodies of water near everything would make the temperatures more even across the day/night and annual cycle. In the summer the oceans are a heat sink, in the winter they give it back ([Continental](https://en.wikipedia.org/wiki/Continental_climate) climate). * Things like the Gulf Stream would be impossible, so I'd expect more regular climates at every latitude. Net result, a very predictable climate. [Answer] Since I am envisioning an entire planetary surface made of isolated squares of deep water, I would expect the lack of currents would result in temperature extremes. The equatorial areas would be the hottest and as the latitude increased North or South, the squares would be cooler. Until you got to the polar regions, which might be frozen solid. If they were one large ocean, then currents would mitigate temperature extremes, but as small bounded seas, they seem like they only get heated by the sunlight they receive. [Answer] Without oceanic circulation, the seas in tropical latitudes would evaporate in short time (I guesstimate hundred years) and water deposited toward poles. Poles likewise without being warmed by currents, would end up with large stable ice caps, and only two relatively thin strips of moderate latitudes would stay habitable. Such widespread change could even topple the climate into ice age, planet with large ice caps and frigid desert between them. Over the scale of millions of years, if the aliens did not disable plate tectonics, these will disrupt the setup and larger oceans/landmasses will reemerge. ]
[Question] [ There is a forest in my world with a special property: All the trees are optimised to shade as much as possible during summer and give as little shadow as possible during winter, to regulate the temperature of the ground through sunlight. Is it possible to have such a spindly tree with large leaves? My concern is not how this is possible, but how a tree could develop to have as little stem and branches as possible while maximising the surface of foliage. The trees in our world aren't 'built' with this shadow-reduction in mind, which is why I ask whether it would be possible. I could imagine structural integrity being a concern, but perhaps one could work around that? PS: Should I make this an "Anatomically Correct" question? [Answer] You presumably want large leaves because they might shade better, but you can shade just as well with a denser canopy of smaller leaves. You presumably want really thin spindly trees to maximise the amount of sunlight that can reach the ground in winter, but that present a bit of a structural issue. For a start, what would happen in strong winds? Nothing good, I suspect. So let me suggest three other possible choices. (I hope its ok to put multiple answers in one answer!) Idea 1: Do you know what the best way is to maximise the amount of sunlight reaching the ground in winter? Get rid of all the trunks entirely. Why not invent something a little like bamboo, which grows densely and rapidly in the spring but unlike real bamboo it flowers, seeds and dies before the year is out. Maybe it grows from a dense underground [rhizome](https://en.wikipedia.org/wiki/Rhizome) so it doesn't really "die" each year as such... only the above ground portion withers away. Bamboo can be pretty dense already in real life; it wouldn't require much tweaking to make it even better for the purposes you'd like. Maybe fill your forest with hibernatory panda-analogues which help eat all the annual shoots. [![bamboo forest](https://i.stack.imgur.com/5RcyA.jpg)](https://i.stack.imgur.com/5RcyA.jpg) ([image source Lenny K Photography](https://www.flickr.com/photos/lennykphotography/24737378890)) Idea 2: Sunlight reaching the ground is absolutely not the only thing that affects temperature. Consider most equatorial deserts... baking hot during the day under that intense sun, but pretty cold at night because all the heat radiates away. What might be useful, then, is the opposite of conventional [nyctinasty](https://en.wikipedia.org/wiki/Nyctinasty), a process whereby plants close up leaves and/or flowers overnight. Instead, your thermoregulatory plants don't shed their leaves in winter, like a [deciduous](https://en.wikipedia.org/wiki/Deciduous) tree might (which is another simple answer to your question, incidentally), but instead keep them as a sort of zombie canopy that isn't used for photosynthesis. The leaves fold shut during the day, allowing sunlight to reach the ground, then spread out again during the night to help trap a layer of warmer air. If the canopy is dense enough, this will have a measurable effect. This wouldn't be recommended anywhere which gets really cold, or experiences significant snowfall, because those leaves could freeze and break off, rendering them useless, or the accumulated load of snow could easily causes branches or whole trees to break. [![thigmonasty](https://i.stack.imgur.com/SWlaD.gif)](https://i.stack.imgur.com/SWlaD.gif) (this shows [thigmonasty](https://en.wikipedia.org/wiki/Thigmonasty) rather than nyctinasty, but the movement is indicative of what what leaves are capable of) Idea 3: A single skinny trunk has structural problems, but these can be worked around if you have an aerial root system and/or [stolons](https://en.wikipedia.org/wiki/Stolon) (also known as runners) that give your plant multiple separate props spread around in an area. A real world plant which is a little like this is the [banyan tree](https://en.wikipedia.org/wiki/Banyan), a sort of vine that can eventually form thick, woody trunks and descending roots from cross-branches so one plant can look like a whole grove of interlinked trees. Real world banyans have quite thick trunks, but the same strategy could be used for thinner structural members, I'm sure. [![banyan tree](https://i.stack.imgur.com/NaAMl.jpg)](https://i.stack.imgur.com/NaAMl.jpg) ([image source Kandukuru Nagarjun](https://www.flickr.com/photos/nagarjun/15289808604)) [Answer] I goofed and got my seasons reversed initially. The OP, as some kind commenter pointed out, wants cool summers and warm winters. This is a much harder problem. The plant needs to absorb light to get energy. So... Two notions. ### Selective reflection. Leaves only absorb the light they can actually use for photosynthesis, and reflect the rest. Typically plants only use a few percent of the incoming energy, so they could be nearly white. This would in effect make vegetated areas about as reflective as dirty snow. Call it 85%. ### Annual heat storage. The circulation of these plants is active, possibly even having 'hearts' that rapidly move sap between leaves and roots. Excess summer heat is used to warm the entire root zone. Couple this with deep rooted varieties, and you have the thermal mass of 10 meters of earth. Earth runs about 1/3 that of water on a per volume basis for each storage. So, about 700 BTU/cubic meter/degree F. If you can get a 20 degree differential between winter and summer. (about the same as surface soil temp changes) you have 14000 BTU per square meter. This isn't enough. The solar constant is about 5000 BTU/m2 at the top of the atmosphere, about 3000 on a clear day. Because the earth isn't flat, and one half is in the shade, that's 750/hour on average. Earth is about 30% reflective, so 500/hour/m2 net. So the earth heat sponge holds about a month's worth of solar energy. This is sufficient to warm up your winters a bit and cool off your summers a bit. Basically you are converting a continental climate into a somewhat more maritime one. Ok. Time for some heavier ammunition. Your oceans are filled with filiment shaped algae that are somewhat stiff. They are like kelp, and live vertically. But they pump heat from the surface deep into the water. The net result is that you warm the top 50 meters of ocean. This holds about 15 times the amount of heat tht plants on land do. Side effect of this: You may have some extreme hurricanes from hot surface waters. --- Original answer This already is what trees do. Look at the forest floor of a spruce forest. It's DARK dark enough that almost nothing grows there. Human eye adapts to low light quite well, so it doesn't seem that the light level in a forest is only 1/20 or less than in full sun. All you really need is a variant of chlorophyll that doesn't reflect green light. Easy to make the entire planet dark grey. To get the opposite effect in winter, the trees have white bark, and the leaves on the ground decompose into a white pigment. Not sure how you want to handle oceans. Could have black algae for summer, but when light levels are low, it reverts to white. ]
[Question] [ In my setting, centaurs are related to other six-limbed creatures such as dragons and griffins (the "fur" is actually made up of tiny feathers). Assuming they were originally creatures similar to six-legged, wingless griffins or dragons, would it make evolutionary sense for them to develop humanoid torsos, arms, and heads? [Answer] I imagine it would be possible, though there would be many differences from traditional centaurs (like not having a navel on the humanoid torso). A real-world counterpart is the praying mantis (picture), where the foremost legs have evolved into something like arms, supported by a thin torso. If a six-legged walking species evolved to use its front paws as hands, a more upright stature of the front torso would make sense, and you could get something vaguely centaurish. It might have a double stomach, one in each torso, for pre-digestion and digestion. The lungs would probably have to be in the larger 'horse' torso. Or else the 'human' torso would hold lungs, while the 'horse' torso would hold the stomach(s). If dragons and griffins lay eggs, that would likely mean that your centaurs do, as well (though there are examples of fish giving live birth, even though most fish lay eggs). This would mean that they aren't likely to suckle their young (unless dragons and griffins do; like a platypus, which lays eggs and suckle their young). This means no nipples and no breast on the females. An issue might be the size of the mouth, both for breathing and eating, but possibly centaurs have larger heads than humans, with broader mouths and bigger nostrils. Also, do they have hoofs, or rather claws like their relatives? Are their eyes reptilian/avian? You would probably not be able to mistake such a centaur from a horse with an added human torso, but they could be quite centaurish. [![enter image description here](https://i.stack.imgur.com/g7TQE.jpg)](https://i.stack.imgur.com/g7TQE.jpg) [Answer] I would say, if you do not need them to be directly related to each other, you would have easier time to explain them away. I do not know the precise details of your world, and whether there are more familiar four-limbed animals there, so I use an alternative Earth as an example. Say, there is a continent similar to Australia, that become isolated much earlier and much more severely due to whatever cases - geological conditions, change in ocean currents, weird patterns of glaciation. So it became isolated somewhere in the period corresponding to our Devonian period. And the fish that first walked on the shore happened to have three pair of fins instead of two. It could be a suboptimal development, but in the isolated conditions it gave start to the whole plethora of six-limbed land animals. If the isolation continued through the millions of years, you would most definitely have the cases of parallel evolution and there would be hexapod reptiles, hexapod birds and hexapod mammals. So, your griffins, dragons and centaurs, as well as thousands of other hexapods, are another, isolated offshoot of bony fishes, a clade in the same order as more familiar to us tetrapods. If, again, the isolation of the continent stopped some time ago, due to natural or man- (or centaur-) made factors, the ecosystems would begin to mix. Some of the hexapods could survive being introduced in the tetrapod environments, and so they would spread beyond their native environments (could be used to explain, why there are only dragons and griffins around, while smaller hexapods didn't fare so well). Centaurs, being sapient tool users, would generally be better at withstanding evolutionary pressures. [Answer] No. Having a torso would require moving your lungs and heart from the body of a horse like creature into a human torso. Not only would you be shrinking your lungs and heart down to a human size, your heart would need to work much harder to pump blood to the far extremities of your body. You might get away with having a second heart, however since humans breathe through their nose, you're going to have to take huge breaths through a fairly small nose. If you haven't noticed, horses actually have huge nostrils. However since this is your world, you can do what you want. Using the help of magic or special evolution lines in creatures it is possible to have them distantly linked together. As an extreme example, The scorpions of my world are capable of evolving/devolving into octopuses. It goes something like Scorpion <-> Lobster <-> Crab <-> Octopus. Of course, my world has magic which gives me a lot of wiggle room. [Answer] Im going to say no, and here's why hexapedal creatures on other planets/worlds are plausible if not inevitable; that is not up for debate in my opinion. However, I would say that animals on earth and I assume other planets would have body segments that "match-up" one of the main issues I see with most centaurs people design is they are chimerical rather than discrete, that is to say, they look like Frankensteins rather than living breathing beasts. If you create a reptilian or feline-like creature with a simian upper torso up shooting from its "shoulders" you are gonna create something that gets weird looks and enters into a darwin's uncanny valley. Unless your creature resembles a gorilla or chimp bellow the "belt" I wouldn't put a humanoid-human-like form above it. Some people have pulled off some cool alien centaurs one of which is JayRockin-definitely talk to her if you get the chance she may be able to help you more than I can. If I was going to design a centaur (let's say a bear-like centaur) I would first duplicate either the shoulder girdle or the pelvic girdle of the animal and extend it forward and back, this way I'm working with decent parameters. Then I will edit the forelimbs to my liking while keeping them discrete and so forth. If i were to do internals I would anchor the arms to the false rib cage and should girdle and make the viscera longer and keep most things except for the esophagus, brain, primary heart in the lower body. I could in theory reference some large invertebrate to position organs and edit the external orifices to match. @Klaus Æ. Mogensen rose fantastic points. You will have to divide the viscera with reason. things like water bears, arachnids(scorpions), and mantises are a good reference. I do not know however how your creatures breath, what sort of blood they use, where ears are, or what the basic "hexapod" skeleton looks like in your world; so I may not be able to give you too much feedback. [![If your creatures breath via spiracles like many invertebrates you could have many entries for air- but they may not respirate aswell as a horse.](https://i.stack.imgur.com/sX3ER.png)](https://i.stack.imgur.com/sX3ER.png) [![spider guts be all over the place](https://i.stack.imgur.com/XxFFk.png)](https://i.stack.imgur.com/XxFFk.png) (a sketch i did) <https://cdn.discordapp.com/attachments/332688484173217822/582386815189909504/unknown.png> [![some taurs by Jayrockin on FA](https://i.stack.imgur.com/F0R9d.png)](https://i.stack.imgur.com/F0R9d.png) <http://d.facdn.net/art/jayrockin/1442396298/1442396298.jayrockin_aliencentaur1.png> ]
[Question] [ I am writing about a blood magic cult, and they drink/paint with collected blood to preform rituals and bursts of magic. Most of their supply is garnered through the use of human cattle, but in a pinch blood of other animals can give some power (but the power is greatly reduced). The story takes place in a mythical setting, but I would like to stick to creatures found on Earth. I know primates have similar blood, but what about other kinds of animals? It would help my story to have a list of non-primate animals that have blood similar to human blood, and figured this would be the place to ask. The best answer would have a few animals with very similar blood, a few animals with extremely different blood, and a short explanation of what makes it so. [Answer] In general, blood is not under significant selective pressure, and when it is - e.g. elongated erythrocytes of camels - it's usually confined to the odd species rather than whole higher taxa. As such, genetic drift should be the main driver of blood changing over generations. Therefore, the further phylogenetically we go from Primates, the less and less similar the blood will be. In order of similarity, a list would by this reasoning go like this: * Colugos * Tree shrews * Rodents, rabbits, hares & pikas * Ungulates, carnivores, whales, bats, pangolins and shrews & kin * Anteaters, sloths, armadillos So, colugos would be the absolute best non-primates for blood. They;re only found in Southeast Asia, though, as are tree shrews, so perhaps rodents would be the best bet - they're cosmopolitan, and wherever they're found they're really damn common. [Answer] I recently read online a somewhat improbable theory that the first humans were hybrids,the result of intercourse between chimpanzees and wild pigs. A rather dubious theory, but no doubt suggested by the many biological similarities between humans and pigs. <https://phys.org/news/2013-07-chimp-pig-hybrid-humans.html>[1](https://phys.org/news/2013-07-chimp-pig-hybrid-humans.html) As a matter of fact, pig blood is similar enough to human blood that there is serious medical interest in ending blood shortages by using pig blood - possibly genetically modified pig blood - for transfusions. So it is possible that pig blood might someday be used for medical transfusions, which makes it seem like pig blood is a rather good candidate for nonhuman blood that is most similar to human. <https://en.wikipedia.org/wiki/Xenotransfusion>[2](https://en.wikipedia.org/wiki/Xenotransfusion) <https://www.quora.com/Can-pigs-blood-be-used-as-a-substitute-for-human-blood>[3](https://www.quora.com/Can-pigs-blood-be-used-as-a-substitute-for-human-blood) <https://nypost.com/2000/12/18/pig-to-man-blood-transfusion-may-be-just-the-start/>[4](https://nypost.com/2000/12/18/pig-to-man-blood-transfusion-may-be-just-the-start/) [Answer] Any mammal that is not a camel Every mammal except camels (which have nucleated red blood cells) have blood that is more or less the same. The only real difference is the receptor proteins covering the blood cells' surface, and the only reason we don't use animal blood frequently in transfusions is the immune systems of the recipient don't like it because of incorrect receptor proteins and attack it. If you aren't using it for transfusion there is no reason for human blood to perform differently from any other mammal's blood unless you have some rule of magic in-universe that somehow marks human blood out as special. But from a biological standpoint human blood isn't special beyond the fact that it originally came from a bipedal, mostly hairless primate body instead of a deer, cow, or dog. ]
[Question] [ The first in a series of questions on building a realistic sedentary centaur culture. From what I have encountered, centaur civilizations are usually modeled on (semi)nomadic cultures from the Eurasian steppes or the North American plains. In contrast, the centaurs in my world have developed a sedentary civilization, complete with farms, villages, and large cities. This question is aimed at figuring out which animals you would find in these centaur communities. Now, I am aware that domestication is a long and difficult process, and demands a lot from the animal one is looking to domesticate. For the context of this question, assume that this is not an issue. This is my view on the why of humans domesticating animals: Humans have domesticated a variety of animals for different purposes, each species providing us with something we need, or helping us accomplish something in an easier way. These needs are dictated by our bodies. On to the centaurs. The humanoid torso part of the centaur is the same size as your average human torso, with the equine parts sized to match. Strength-wise, the equine parts are comparable to horses, and the humanoid parts are comparable to humans. Intelligence is equal to humans. Assume a diet comparable to humans: omnivorous, with a preference for cooked food. The title question can be separated into two parts: 1. What animals would centaurs domesticate that humans have not, and why? 2. What animals that humans have domesticated would centaurs leave undomesticated? As to where you may look for animals to domesticate, all biomes are fair game, from fertile, open plains to dense rain forest, to deserts (both hot and cold), mountains and lowlands, arctic, anything. These centaurs live anywhere humans can. [Answer] Even though your centaurs are sedentary, their equine portion will still require exercise so a sedentary existence for a centaur is going to cover miles of territory. A natural animal for them to domesticate would be the ostrich. It would replace the chicken in a human's diet as it's larger size eggs and body meat would satisfy a hungry centaur. Herding them wouldn't be a problem either. I image that centaur fashion includes a lot of ostrich feathers - at least in their hats and maybe in pillows. (Do centaurs sleep standing up?) I would also believe that centaurs would take up the sport of falconry and maybe add owls to the mix. Owls could also help control the mice population. Partly because these animals can keep up with an active centaur youth and travel distances. I can also image centaurs keeping snakes as pets and for food and leather. As for farming, I can image them cultivating vine and tree crops - training plants to grow so that harvesting of fruit and vegetables is within easy reach. They might allow themselves to be hitched to a farming plow but they are not going to plant many crops that require them to bend down all day especially to do weeding so raised bed gardening with water feed using screw auger to elevate the water to proper level something similar to the hanging gardens of Babylon. The centaur engineers would be masters of using basic simple machines of wheel, pulley, lever, inclined plane, wedge and screw to overcome some of the perceived limitations to bending or vertical climbing. A major career field might be crane operator. Ship builder, sailor and fisher-centaur would also be interesting occupation for coastal dwellers. [Answer] Cat first, to keep mice from grain stores. Cow second, for dairy reasons like humans did. Horses may be tamed like humans do with monkeys... for novelty, but also to help with farm work. They would probably do a lot more domestication of elephants because they actually get a significant increase in available strength. Also, probably smaller more nimble animals. (Monkeys would probably replace dogs for the versatile domesticated animal) as the major centaur limitation would be their large size in inflexibility. Would not do dogs as a herbivore species doesn't need to hunt, which means they never get tot he other uses. Same with hawk. [Answer] This almost entirely depends on where centaurs originate from. Humans domesticated whatever local animals they could (unless they hunted them to extinction first) then later imported a few others via trade routes and bring animals with them when they colonize. Some animals proved very easy to domesticate and extremely useful on top of that. Those are the ones that got traded brought along during migration. Most of the more common domesticated animals come from the southern half Asia The same places we first see widespread agriculture. Cattle, goats, sheep, and poultry spread fast, since they each have many uses. Pigs have the advantage of eating almost anything and being easy to care for, so expect them to be high on the list as well. But there is a problem here, centaurs are not going to be milking anything, not unless it is job given to young children, or they build special raised floor buildings (unlikely). You have to get fairly low to the ground to milk even cattle. So cattle and goats are less useful. Which leaves you with sheep, pigs, and poultry. But humans (at least successful ones) also tend to adopt animals that do well in the local climate, so camels, llama, and yaks have a shot. Humans that tried to raise animals in the wrong environment did not do so well, looking at you greenland vikings. Then you had human cultures that never domesticated any animals or only one or two because that was all the local environment had and trade was not a option. So really it all comes down to what is available, centaurs will not all have hte same animals. The odd ones out are horses and asses which humans moved everywhere but they are really only useful for riding until you have done a lot of breeding, so centaurs are unlikely to ever bother. Dogs on the other hand are still useful to them for much the same reason they are humans, more so since centaurs are unlikely to have the stamina humans have so they offer even more advantage in hunting and herding. A human can literally walk a horse to death, centaurs will likely have similar stamina to horses, size, fur, and an unguligrade posture do have their drawbacks. It might even be worse since they are stuck with the same large calorie hungry brain we are. ]
[Question] [ I have been looking up a few different theories lately. And one of those is the idea that intelligent life cannot exist for any long period of time without eradicating itself or being destroyed by outside influences. My question assumes all hypothetical life that may exist within 30LY of Earth died between now and 200yrs from now. With humanity managing to obtain a limited form of faster than light travel by 250 years from now. Would the bodies of these life forms still be intact inside of their spaceships in the cold depths of the void? Let me know if this is likely. I suspect they'd mummify but I am not 100% sure. [Answer] It depends on the size of the biological matter. In space you have mainly two factors of hostility: 1. extreme temperatures 2. radiation and energetic particles Extreme temperatures are dangerous for preservation only on the hot extreme, since they break down organic molecules into smaller components. When they are on the cold extreme they are advantageous. Deep space frozen matter doesn't change that much, so the same holds for organic matter. If the freezing is slow, you might get collateral damages by the formation of ice crystals. Here size matters: the bigger the sample, the longer it will take to freeze, as the only way to lose heat in the vacuum of space is by radiating it. And the longer it takes to freeze, the bigger ice crystals can form. Radiation and energetic particles instead bring damage whenever they interact with matter, including organic matter. Since the damage is dose dependent, and the absorbed dose increases with the volume of matter, it follows that the bigger the sample the bigger the damage. So, a human body might get more damage than a bacterial spore. Moreover, a human body is a tad more complex than a bacteria in its working, therefore it's also more sensitive to damages, simply because there are more mechanisms that can get broken. > > Would the bodies of these life forms still be intact inside of their spaceships in the cold depths of the void? > > > Completely intact no, they would be frozen and dehydrated, resembling an Oetzi. However, they would not be rotting away, in reason of their frozen status. caution should be exerted on handling them, as they would be extremely fragile. [Answer] Yes. Since we're talking inside a ship, I think there'd be a very good chance the bodies would still be there. If the atmosphere has been vented, that is. You'd have some very well preserved mummies. The ship itself (depending on the technology) would protect the bodies from the worst of the radiation and from minor impacts. And may even offer some level of protection from heat extremes (though as you seem to be implying deep space, heat probably won't be an issue). This is of course assuming human-like physiology. If the atmosphere is still in place, or for that matter, if the life support system is still working, you'd get basically whatever decomposition would be natural in those conditions for that species. Keep in mind decomposition may alter the atmosphere in the ship, using up O2 and producing CO2. So at some point, if there's not enough of it, it may stall. ]
[Question] [ This is the first part of a series of questions I'll ask about a self-sustaining colonization ship. I'll keep editing this post as things unfold. [Part II - Landing](https://worldbuilding.stackexchange.com/questions/135957/the-colonist-part-ii-landing) Edit 1: Added two movie references to try to make the ship's idea clearer and removed the points that were making this question too broad, as pointed by JBH. Also, life support is not being taken into consideration for physical space anymore. It will be discussed in a further question. --- ## Some Context The setting is kind of a low sci-fi. In this universe there are no FTL drives - in fact, the maximum level of technology is not even close to that. Humans rely on "old fashioned drives" with a little twist. They're more efficient than the ones we have today, but bear in mind that this is a very-near-future-tech scenario (50 to 100 years in the future). Humans are in the early stages of the space colonization era. "The Colonists", as they're known, are huge ships equiped with the tools to ensure the crew's safety and to help populate the new worlds. Since these trips might take decades, the ideia behind the ships is basically the same as seen in [Pandorum](https://www.imdb.com/title/tt1188729/?ref_=nv_sr_1) and [Passengers](https://www.imdb.com/title/tt1355644/?ref_=nv_sr_1) - most of the tripulation is in a suspended animation state while AI's or a minimal crew keep the thing on track. For the sake of simplicity, assume that the colonized planets are exactly like Earth (but untouched by men). For now, this series focuses on the ships and their trips to the new worlds. In order to estabilish boundaries, these trips might take from 20 to 200 years. This first question focuses on the building process of a Colonist. The original idea is that the ships are built completely outside of Earth in Space Shipyards located in orbit (kind of like the ISS). --- ## The Question Is it possible to build such an enormous ship? If yes, is the Space Shipyard a feasible idea? Here's a list of things to consider for this question: * The Moon is a fully terraformed colony in this setting. This colony is able to provide 1/5 of a given raw resource, like iron or wood; * This is a collective effort of humanity, which means that, as long as the Earth and the Moon have the resources to do it, money is of no consequence; * Each ship has to have enough space for: 100 tripulants plus at least a dozen members of the crew, heavy machinery and fuel; * I decided to not take life support in consideration just yet because most of the crew will be in a suspended animation state. There will be another question to deal exclusively with this; * The Shipyard is already there and it has all the manpower and the tools to assemble the ship - but not the materials. They must come from either the Earth or the Moon; * Since we can't know what kinds of fuel, alloys or any other new tech might arise in the coming years, consider the costs for all transportation of materials as half what they are today; * The shipyard idea came from the notion that a ship this big would never be able to leave Earth because of its weight. I don't know if that's correct (but I think it is). In any case, if the shipyard is not necessary, feel free to kill it. [Answer] ## First off: passenger space. (TL;DR: The passenger space would have to be pretty big, but we can cut corners and bring it down to Star Wars size.) If you want to prevent the 100 or so passengers on the ship from getting claustrophobic and eventually insane, you'd have to provide a good amount of space for each passenger, especially if some of them live together. 10 x 10m might be a nice start, since you could most likely fit every basic house thing in that area. However, this already means that the ship would have to be at least 1000 x 1000 m in size for passenger space alone. So, you could instead offer the passengers some form of 'class' system, where the ones who pay more get bigger rooms. Let's say those who opt for smaller rooms get a 6.5 x 6.5 meter space. We'll also say that out of the 100 rooms, 35 are the large ones. So, this takes the ship's total size for passenger space down to at least 772.5 x 772.5 m. When you consider that such a huge area is just passenger space, it might not be super attractive, but at least all the passengers will have a nice time. (For reference, that's about the same length as an Acclamator Class Landing Ship in Star Wars.) ## Oxygen (TL;DR: The oxygen storage, if concentrated in one room, would have to be almost as large as the equatorial radius of Ceres. Instead, we'll opt for a life support system spread across the entire ship's roof, which saves lots of space and only adds a few meters to the ship's height.) Oxygen may or may not be a bit of a problem. Since we, on average, breathe in around 11,000 litres of air a day, over just 100 years all 100 people on board would need about 401,766,420 litres of air. That's about 401,766.4m³. Let's say everyone has personal oxygen systems that don't take up much space and thus we can subtract around 40-50% of the oxygen space. We'd still need 220,972m³ for oxygen space. As a final caveat to reduce this ridiculous required space, let's say we've invented an alloy from tungsten and iron or something. The alloy is ultra-resistant to leaks and therefore we can remove the 10% of extra oxygen we took (just in case). That's down to 198,875m³. Which is still WAAY too much space. So, we'll instead have life support systems in each individual room instead of having one big oxygen storage room, and since space stations like the ISS have it installed along the roof, it takes up far less space since it's spread out. We'd probably only need to add 5 or 6 meters to the ship's roof. We're at 772.5 x 777.5 meters now. ## Leaving Earth (TL;DR: This section is pretty short, so there is no TL;DR.) While the space shipyard idea is presumably more efficient, it adds extra danger since the colonists must take a transport up to the shipyard. The transports could crash and explode. So, let's try to employ some methods to get it to leave Earth from the surface. -A giant magnetic 'sling' on a huge runway, similar to the system that aircraft carriers use but for a giant spaceship. -Simply tilting the ship up and attaching some incredibly strong thrusters to it. This might not be very efficient and could have a high chance of failure. -A runway that leads up to a super-strong launching ramp. With the addition of some medium-strength thrusters, this could get it to escape velocity. Any of those three are doable, as well as the space shipyard. I say you should pick which one to employ. The problem is, the shipyard might be a bit too futuristic, since you'd somehow have to get the shipyard into a stable orbit, and I can't even start there. ## Final Dimensions So since we've sacrificed around 700 square meters for passenger space, we'll have to keep everything else low. The cockpit will probably be the largest of all the extra rooms, since a large crew would be required to control a spaceship of this magnitude. We'll say 10 people man it. A cockpit of around 15 x 15 meters could comfortably house the people, their positions, and all the crazy machinery. There should be a few kitchens and living-room type places to cook up simple snacks and relax with friends. These could be around the sides of the ship and would probably take up about 16 x 16 meters, or maybe a bit more. Since those specific rooms are all we really need, plus maybe an engine room (we'll give all that stuff 50 x 50 meters and put it in the back), we're now at a size of 853.5 x 858.5 meters. Approximately. *That's about the same as a Devore Imperium Warship from Star Trek.* As a few final notes, I'd estimate cost to be around 5,000,000,000,000 dollars, which seems like a lot but would actually be feasible if the entire world came together. Hope this ridiculously long post helped! [Answer] The main issue with long term colony ships of this sort is the mass of supplies and requirement for virtually 100% recycling of everything. This isn't possible with today's technology, but we do know that humans need a certain amount of food, oxygen and water per day, and then try to discover the machinery or mechanism to make up the CLSS (Closed Life Support System). Your ship will then be scaled to carry that amount of mass, plus whatever "backup" materials you think you need (raw materials to "top up" the system, spare parts to keep the system in repair etc. This is a NASA document which should give you an idea of the order of magnitude masses needed: <https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19670025254.pdf> And this is a more modern iteration: <https://ttu-ir.tdl.org/bitstream/handle/2346/73083/ICES_2017_311.pdf?sequence=1&isAllowed=y> The next issue is radiation shielding. Any spacecraft going into deep space needs to protect the crew from cosmic radiation and other events, so will require a massive amount of shielding. The "[Millenial Project](https://www.amazon.ca/Millennial-Project-Colonizing-Galaxy-Eight/dp/0316771635)" (my go to book on these maters) suggests that a shield of water 5m in depth is needed. An equivalent amount of rock or metal is likely needed if you don't want to use water. The mass of the spacecraft can then be calculated by using the shape (i.e. a cone or sphere) to calculate the area and working out the mass of a 5m thick shield of water or rock surrounding it. Since we now have a vessel which is lily the size an mass of an aircraft carrier, conventional rocket technology isn't going to work. The problem is you have to accelerate the mass of the ship, plus the mass of the fuel (including the fuel you are going to use to decelerate at the other end), which means that you are looking at a geometric expansion of mass as you try to increase the ships acceleration or speed. The best way to get around this is to use some form of external power, like a massive solar sail (at this scale perhaps a series of solar sails tehtered together like a bunch of kites). You could either dive close to the Sun and unfurl the light sail, or use massive banks of lasers to drive the sail. > > Paradoxically the way to get out of the Solar System fast is to first arrange that your probes dive towards the Sun with the probes facing edge on to minimize radiation pressure. Then turn almost face on at perihelion(closest to the Sun) and blast away. > > > If closest approach is 1/10 of an Au, the final velocity is: > > > 420 km/sec > > > And if the materials(some sort of unobtanium:)) could withstand an approach to 1/100 Au, only 1.5 million km from the center of the Sun, and therefore only 800,000km over the seething surface(!), the final velocity of our interstellar probe would be: > > > 1330 km/sec > > > Astute readers will notice that just as the escape velocity of a massive body varies inversely as the square root of the starting distance R from the center, so does the final velocity of our Solar Probe. > > > <https://www.quora.com/How-fast-could-a-theoretical-solar-sail-starship-get> [![enter image description here](https://i.stack.imgur.com/WgfhR.jpg)](https://i.stack.imgur.com/WgfhR.jpg) Actually, at this scale, you would not really be able to see the ship. Solar sails will have to be unimaginably large So you will be looking at a very large, very massive ship. Propelling it by diving into the Sun to provide the maximum amount of Solar energy provides the velocity necessary to reach Alpha Centauri in about 1000 years. Presumably the crew at the time of arrival will arrange to "dive" into Alpha Centauri to provide the energy to brake into stellar orbit and then explore the system. [Answer] Location, Location The shipyard is located in the Asteriod Belt, or in solar orbit just past Neptune. Why? * Located in the Asteriod belt, resources are easy to acquire and resources are required in large amounts. * Located in High solar orbit, the launched ship will have the perfect launching position to use the large planetary bodies and the sun itself to perform an initial gravity assisted slingshot. Additionally moving large amounts of mass to the shipyard can be done "safer" as any rogue masses are more likely to be caught by the large planetary gravity wells, or be ejected into cold space. * In either orbit, delta-v requirements are reduced for solar-system escape in comparison to earth orbit. Power Providing continuous power to such a large scale construction project, not to mention any living requirements for humans, is going to take more than can be provided by solar cells at those orbits. Nuclear Fission reactors might be able to do the trick, but these require specific isotopic elements, and produce nasty by-products. Alternately Nuclear Fusion reactors (while still requiring specific isotopic elements) don't produce nasty by-products, but also currently don't produce any net-positive power. Perhaps this would be possible in a few decades, perhaps not. Also we have not considered how the ship itself will be powered once launched. Doubtlessly the design will contain multiple redundant systems, but operating its own power plants will require consumable resources, and what do you do with the rubbish? Thinking large scale what about a Dyson Array? Even a very modest array will provide power in copious amounts for not only construction, but also for transmitting to the vessel for 200+ years. Transport People moving to and from the shipyards can be provided by a smaller 500+ person ship. Again powered by a mix of solar, reactor, and dyson array. The engines can be ion based, with a solar sail carefully pushed by the dyson array. Mining Perhaps the most complex operation, while the asteriod belt contains resources this would present some difficulty for humans to extract. Robots could do the job, but we are still fumbling the robotics in our own factories on Earth as Tesla can show. A near term source would be a mining colony on the moon, or mercury. * The moon has hassles in terms of atmosphere, and cosmic radiation. * Mercury has hassles in terms of gravity Life Support This is the most difficult aspect. We aren't sure what is needed for long-term health in space, even within the solar system. The best bet is to engineer the space station to provide something convincingly earth like: Atmospheric pressure, actual terran biomes, gravity, and sun-like light. The best design for this is actually a ring (or rings) with a central counter rotating shaft for docking, and engine mounting. The ring should have a circular cross-section to maximise both internal space, and strength of the overall structure. If there are multiple rings, perhaps some cross ring bracing for extract structural stability. So as to not induce too much discomfort the rings should have an inner diameter of at least 3km. The cross-sectional diameter will depend in large part on the resources available, assembly technique, etc.. Bootstrapping the First Shipyard The first such shipyard would be constructed modularly from Earth, not unakin to the ISS. The modules would be connected at angles to each other forming a small ring. It could probably only rotated to emulate <1/6 earth gravity. Enough to allow work crews to begin fabrication of the actual ring. This inner ring might be kept on the final station as a maintenance yard, or it might be detached to start construction on the next station for deployment elsewhere in the solar system. Resourcing this proto-shipyard will be difficult, as resources from earth are expensive. Moving this proto-shipyard to lunar orbit would be one option. We currently posses technology sufficient to establish a space-elevator on the moon, providing a cheap way to move resources to the proto-shipyard. Alternately as the moon is very important to the Earth-Moon system, pilfering resources from the moons of mars would be easier as they have less gravity. Though this will make the human logistics harder. Once the proto-shipyard has constructed the first shipyard, humanity can really start building at scale the generation ships. ]
[Question] [ (Beforehand I'll excuse myself for my english. If you didn't need to know that you can just ignore it) There's a network of root-like life forms in the top layers of my planet. They use some kind of synthetic bacteria to get energy out of chemical compounds. Also they use the warmth of the planet to grow... The outer forks of these systems are thinner than human hair. They only start growing when they detect materials the "mother system" can use to mine it and transport it. If a big fork isn't needed any longer it dies and gets eaten by smaller ones. The biggest roots serve as storage and also function as reliable transport routes through harsh terrains like a desert or even an ocean to link two big systems together. When two big systems "find" each other, the two biggest roots start winding around each other to share as much surface as possible over which they can pass resources. Eventually they will build towers like that. These "root towers" are the most important part to me because their iconic design should set the background theme of my world. Many animal-like creatures will use them in many different ways. The problem is that I want them to be very thick and up to higher than a mile. I don't worry as much about how the towers can get this high because there's enough carbon and network with trillions of roots will have enough energy left. I worry about why the roots would evolve this way. Now... Why would they grow like that? I only have a few explanations and they can't stand on their own. 1. I'd explain that they grow vertically because the root systems would use pressure and vacuum supported by gravity to send and receive resources. 2. Another attempt is that they would have to grow way up to reach gases and sunlight which they need to build certain molecules. The system would use these molecules to get a picture of where their resources should be sent to. The higher the concentration of these molecules in a root, the more of the requested resources it gets. 3. This sounds silly to me, but the root system could use these towers to protect a big (and very high) store of reserves from creatures that eat roots underground but not on the surface. Not energy efficient, but hey... --- What I want I want one single solid explanation to why the towers would grow this big. The readers shouldn't ask themselves much more about the towers and they should just accept that they are a scientifically logical thing to exist. How far off do you think I am? Do you have a better explanation than any of mine? Do you have any other advice for me? Thank you in advance [Answer] In a competitive environment such as forests and jungles, plants on Earth need to grow vertically and quickly to outcompete neighbours in [the quest for light](https://en.wikipedia.org/wiki/Canopy_(biology)), which for a plant is essentially food and therefore survival. Extending your canopy above others not only gives you more light, but also restricts the light (and therefore growth) of the plants around you and gives you an advantage in offspring and longevity. In your world however these plants appear to grow from 'thermal energy', presumably from the ground. So there may be several logical reasons why they need to form towers: * Competition - such as [Size-Asymmetric competition](https://en.wikipedia.org/wiki/Size-asymmetric_competition) - The ground is already saturated with existing competing plants, and it is easier to attain 'thermal energy' from atmospheric / sunlight than to displace and compete with them. * [Reproduction purposes](https://en.wikipedia.org/wiki/Spermatophyte) - many large trees have the ability to cast their seeds far and wide. In fact, the further the seed travels, the more resilient the species. Height gives you an advantage in this respect, being an enabler of 'helicopter seeds', spores or transmission of seeds through animals or other inhabitants, whereas on the ground you are severely restricted. * [Sexual purposes](https://en.wikipedia.org/wiki/Plant_reproduction) - plants on Earth developed very slowly until Sexual Reproduction, enabling much more biologically diverse and resilient species. Flowering plants are an example, where insects pollenate successful trees, spurring on competition and eliminating mediocre species. In your world, your tower roots may be another form of Sexual Selection, attracting pollinators (or attracting / catching spores or some other gametes) via increased height and capability. This is a strong driving force for evolution, taking precedence in many cases over survival. The world of plants is wide and varied, and I would not be surprised if you find a close example already extant on Earth. [Answer] Altitude. While your plants can grow and thrive underground and just above ground level, they only flower and fruit in high altitude. Originally they existed in more mountainous regions but they have evolved to grow taller as the moved (via seed or root) to lower elevations. They can spread with roots alone but reproduction via seeds is necessary for their long-term health and for genetic diversity. Animals can eat fallen fruit if these plants are rooted in high altitude regions but of course there's nothing left if fruit falls a mile. So animals have evolved synergistically with the plants to be able to climb or fly high enough to reach the fruit. They spread the seeds through their excrement. Some survives the fall but other amounts aren't excreted until after the animal returns to the ground and goes elsewhere. Why the plants wouldn't evolve to be able to fruit in lower altitude is a mystery but evolution sometimes takes twists you don't expect. Your world may have, as you suggest, gasses that separate out by air pressure that the plants need. Or it may have a cloud or ozone layer that the plants must go above. [Answer] For the Plant species to Survive, they've been forced to chase the sky These structures are used in mating and seed propagation, which requires pollinators to accomplish. Previously these pollinators were able to live close to the ground, but for some reason, evolution pushed these pollinators high into the sky. Possibly due to their diet becoming skybound, a new predator scaring them off, or an environmental change that forced them skyward. As time progressed, these pollinators only fly higher and higher, to where the plant structures then had to reach ever higher to perform their reproductive purposes. These structures may be topped by nests of these pollinators, potentially being the only safe home for these beings today. ]
[Question] [ I'm asking this question as a reference for use in worldbuilding when developing world size, atmospheric content, or alien optometric abilities (aka, vision). While I'm specifically asking two questions, their relevance is so close that it's more practical to ask them once, together. Given... * A sphere 10 Km in diameter * It's homogeneous (the material isn't relevant) * Having an [albedo](https://en.wikipedia.org/wiki/Albedo) of 70% (similar to fresh snow) How far away can that sphere be... A) In space, with Sol at the observer's back, the observer 1 AU from Sol? B) In space as in (A), but assuming for the purposes of this question, that space is filled with an [aether](https://en.wikipedia.org/wiki/Aether_(classical_element)) in all ways equivalent to Earth's atmosphere at sea level? And still be seen (even if its shape cannot be clearly distinguished, i.e., a "point") by the average human eye? Assumptions 1. I understand that eye sensitivity to light and focus vary between people. I don't know how to specify the "average." If someone can provide metrics that would clarify this issue, please leave a comment and I'll add them into the question. 2. For the purpose of this question, please ignore the lack of ground. I understand that light reflecting from surfaces between the oberserver and the observed will contribute (substantially, I suspect) to whether or not an object can be seen at a distance. I could be wrong, but I believe the basic setup I've proposed represents a best-case scenario. 3. For the purpose of this question, please ignore the fact that the sun isn't above the observer. In other words, it's shining from behind the observer rather than above or on top of the observer. This effects the amount of [Rayleigh Scattering](https://en.wikipedia.org/wiki/Rayleigh_scattering) that would also contribute to visibility. Once again, I suspect this makes the setup a best-case scenario. 4. Ignore the fact that our hapless observer is sans-spacesuit. In other words, there's nothing about his/her environment as the observer that's affecting his/her vision (no faceplate). Lucky dude, as otherwise the eyes would have a bit of trouble in the vacuum of space. 5. The atmosphere between the oberver and the observed is uniform. This is different from the conditions of a planet (convex) or the inner surface of a Dyson sphere or ringworld (concave) where the atmosphere density is not uniform along the sight path. 6. Please ignore the field of stars (assume they aren't there). This isn't a test of how well a human can identify one tiny mote from a field of tiny, shining motes. A curious thought... Please note that there may be a considerable difference between the sun behind the observer and the sun above and midway between the observer and the observed as the reflection off the sphere may (may...) be greater in the later case. However, it would only be greater on the top half of the sphere (closest to the sun) while it would be lower on the bottom half (and all the Rayleigh scattering issues come into play... and the sun's in your eyes...). At this time, I'm thinking that placing the light source behind the observer produces the highest reflectivity and lowest optical distortion for the greatest distance. If the math says I'm wrong, please let me know. [Answer] # Calculating apparent magnitude Your alignment of the sun, the observer (in space), and the object is as so ``` 1 AU r AU (Sun) ------------- (obsv) ---------//------------(obj) ``` Given that, there are three separate calculations. First is the magnitude of reflected incident energy from the sun. The second is the magnitude of reflected light, given the difference in visible disk of the object, compared to the sun. The third is the brightness of this light to the observer. An issue here is that luminosity is a full spectrum measure of energy output, but we are only interested in energy from the visible spectrum. Since I can't find a visual spectrum only luminosity for the sun to do an energy calculation, we can use the [absolute magnitude](https://en.wikipedia.org/wiki/Absolute_magnitude) of the moon (+0.25) as our starting point. We must adjust the magnitude of the moon by four factors; as each of these factors increases, the object will be relatively dimmer: * Squared ratio of distance from sun to object to distance from sun to moon * Ratio of surface area of the moon to surface area of the object * Albedo of moon to albedo of object * Squared ratio of distance of object to Earth to distance of moon to Earth A difference of $n$ visual magnitudes is equal to a difference of a factor of $100^{n/5}$ in luminosity. Thus, the logarithm base $100^{1/5}=2.512$ of these ratios is summed. We will use $\log$ to represent $\log\_{2.512} = 2.5\log\_{10}$ for simplicity. The distances are straightforward, and are calculated in terms of AU; the moon is roughly 0.00257 AU from Earth. The surface areas of the moon and object are proportional to the radii squared. The object has a radius of 5 km, while the moon is 1738 km. The albedo of the moon is a paltry 0.12, while the object is an incandescent 0.70. We get the following equation for [apparent visual magnitude](https://en.wikipedia.org/wiki/Absolute_magnitude#Solar_System_bodies_(H)) of the object: $$0.25 + \log\left(\frac{(r+1\text{ AU})^2}{(1\text{ AU})^2}\right)+\log\left(\frac{1738^2\text{ m}^2}{5^2\text{ m}^2}\right)+\log\left(\frac{0.12}{0.70}\right)+\log\left(\frac{(r \text{ AU})^2}{(0.00257\text{ AU})^2}\right) $$ # How far away can we see this object? In a big city at night you might only be able to see a magnitude 3 object, while on a moonless night in the middle of the ocean you could see a magnitude 8 object. Lets say that you can see a magnitude 6 object. Attenuation by the atmospheric mass directly overhead is about 0.145 magnitudes; that means that if we were in space, we could see a magnitude 6.145 object. I take the above equation and, for values of r in AU, plot the apparent magnitude of the object on log scale. [![enter image description here](https://i.stack.imgur.com/2OmWe.png)](https://i.stack.imgur.com/2OmWe.png) The code is here: ``` >>> import numpy as np >>> func = lambda r : 0.25 + 2.5np.log10((r+1)2)+2.5np.log10(17382/52)+2.5np.log10(0.12/0.70)+2.5np.log10((r/0.00257)2) >>> x = [x/2-10 for x in range(22)] >>> y = [func(np.exp(i)) for i in x] >>> plt.plot(x, y) [<matplotlib.lines.Line2D object at 0x7fdb949d7eb8>] >>> plt.xlabel("Distance from Earth in exp(x) AU") Text(0.5,0,'Distance from Earth in exp(x) AU') >>> plt.ylabel("Apparent visual magnitude") Text(0,0.5,'Apparent visual magnitude') >>> plt.show() ``` The solution for apparent magnitude 6.15 is 0.00027 AU. This is 1/100 the distance from the Earth to the moon, 41,000 km; or, roughly, geostationary orbit.** [Answer] In aviation, part of the daily forecast is the estimation of unobstructed visibility. Obviously at a reasonable altitude, the curvature of the earth is no longer a factor, so physical obstructions, including fog and clouds are generally the obstructions. 10 statute miles is the maximum value for a clear day. I have never seen a value greater than this. It would be a good starting point. ]
[Question] [ Closed. This question is [opinion-based](/help/closed-questions). It is not currently accepting answers. --- Want to improve this question? Update the question so it can be answered with facts and citations by [editing this post](/posts/128523/edit). Closed 5 years ago. [Improve this question](/posts/128523/edit) I've created a world that is filled with beings and creatures that are very specific that can be easily separated and recognized. In this world there are seven (7) basic types of lifeforms (not counting bacteria, viruses and other micro-organisms). Basic differences are their food sources. Types: * Rocky family - mainly eat plants and feed on magic-like energy that is all around them in nature. * Humans - eat normal human food ( meat, plants, etc.) * Basic animals - ( animals that are a food source for humans ), grass and low bushes * Nature protector animals - ( These animals are not a food source for humans and have been given some magical powers and serve to protect the nature ) Eat small "Basic animal" and live on the energy provided by the magic in the air * Phantoms eat anything except plants, and cannot live on the magical energy * Live plants mostly act like "sand traps" eating any flesh The final category is a creature that is made from a colony of small magical creatures. They eat any kind of plants or animals, and are parasitic and can swarm like or locusts. I need to somehow limit them from destroying a large amount of land. My current idea is that they should only be active at specific times of the year. Is this a viable solution to reasonably prevent these types of creatures from destroying my world? [Answer] > > Live plants mostly act like "sand traps" eating any flesh given to them (...) I need to some how limit them from destroying a large amount of land at once. > > > "Live plant" is a misnomer. Being lifeforms, plants are by definition living beings just like animals[citation needed]. Other than that, carnivorous plants are a thing in our world. In some forrests and jungles you can find many venus flytraps and other species. The bigger ones will feed on rodents and frogs, even. The very largest one may as well be Puya chilensis, which attracts sheep that then get stuck in its spikes and die, fertilizing the soil with their corpses. These buggers have so far failed horribly in "destroying a large amount of land at once". If your carnivorous plants can move around, then they are no different from regular predators. If they hunt by making traps as you suggest, then they are like antlions and spiders, although their prey may be quite larger. [Answer] You want to protect your world? Isn't that what "Nature Protector Animals" are supposed to do? [![whale eats fish](https://i.stack.imgur.com/6Lhb3.jpg)](https://i.stack.imgur.com/6Lhb3.jpg) <https://www.nwf.org/Magazines/National-Wildlife/2015/AugSept/PhotoZone/Brydes-Whales> You have already in your list a class of creatures which "protect the nature" and eat magic and small animals. You are worried that your magic bug swarm will destroy the nature. I observe that the swarm is both magic and small animals - delicious! I propose that when the bugs start doing their thing, large Nature Protector Animals of various sorts will arrive in short order and devour them. [Answer] Are you asking who would eat the "small" animals? If they are like IRL rats or mice, they should be eaten by same predators that eat larger animals. IRL, wolves and foxes and various wild cats eat both large animals like deer, and small animals like rats or mice. In your world, it sounds like "nature protectors" serve the same role, since they already eat mid-sized herbivores. [Answer] So you have a group of probably aggressive plants that like to eat meat. Look at the carnivorous plants that exist in the real world. The sort of it, as far as I understand, is that real carnivorous plants live primarily in nutrient poor soil. What they eat is still the energy from sunlight to make sugars, but they need more than that. Meat provides that supplemental nutrition. So that's why they eat animals. Nature provides us another example in common weeds. One aggressive weed will choke out competing plants in the same patch of soil. That'll give you some Why's for why your Live Plants doing what they do. It can also give you some directions in limitations. Soils throughout the world vary a lot, depending on a variety of conditions. That alone gives you a very solid reason for limiting the range of your very hungry plants. Perhaps they initially grew in areas that are swampy. That means they aren't going to spread readily toward more well drained soil. The water requirement may be too high. Maybe they evolved in an area that had highly acidic soil, like azaleas or roses. Those won't thrive unless you give them some specific types of fertilizers to alter the pH of the soil they are in. That give you another reason to limit range. The types of local animals are equally influenced by the local plant life which is in turn influenced by soil. So you get low grasslands. In turn you will probably get relatively small animals like mice and voles and bunnies. If those are the predominant animal, the Live Plants will evolve to eat the most common animals, which aren't that big to begin with. Hopefully that'll get you where you need to be. [Answer] Your creatures sound like magic Locust. The Locust swarms on earth ebb and swarm based on the availability of food, seasons, and their reproductive cycle. Have a look at the [Desert Locust (wiki)](https://en.wikipedia.org/wiki/Desert_locust) for ideas. They reproduce 2 to 5 times in a year, so the swarm or "upsurge" is really the children or great-great-grandchildren of the initial hatching. This could be a viable mechanism for your creature, especially if you intend to have an ominous stage in your world where the first sightings of the creature cause people to start trying to exterminate as many as possible before its too late to prevent an upsurge. [Answer] Food availability, seasons and predation. Since food availability cant drop too much or it'll mark the land as destroyed you limit them through their magic. Their brand of magic (or all magic if you like) ebbs and flows. This can ebb and flow over time and even vary from location to location. This means they are limited in time and what area they can feed on. Better yet, they might only follow magic around and while they might eat a lot as they pass they dont stay long enough to deal damage. Seasons. Like any small creature, seasons can heavily influence their number. First food becomes scarcer and then the cold (or heat, depending on the area) kills off a lot leaving few to build up their numbers again. Predation. As with most creatures that generate lots and lots of offspring, the local wildlife learns how delicious they are quickly. Ducks for example get dozens of ducklings per cycle but only a few make it to adulthood. And whenever a small critter or insect manages a baby-boom, it's predators will shortly after have a baby-boom of their own as food and energy is easily accessible and more predators reach maturity. ]
[Question] [ So, in my story there is a species of aliens, called the Ko’dor. The Ko’dor are a species of shape-shifters, who can change their forms at will. Naturally, they are four-eyed, green octopus like creatures. But, they have the ability to morph and change to human, or any other species's, shape. But, to the Ko’dor, shape-shifting takes a lot of muscle bending and skin folding. A Ko’dor spy has just entered your spaceship. The Ko’dor is unnoticed at first, but once he accidentally spills over a salt tin in his quarters, he dies. I can’t let my main characters know the spy is there yet, so the Ko’dor has to stay in his human form, even while dead. Since muscles normally relax after death, why might Ko’dor biology allow them to stay in shapeshifted form, even while dead? [Answer] Your Ko'dor aliens need a voluntary physical effort to change shape. If they don´t activate the muscles and the skin to return to their original shape, the process won´t happen. That is an evolutionary advantage, because if they are left unconscious or if they sleep, they mantain their current modified shape. The only way to know they are not humans is by means of an X-Ray scan, a blood sample, or a trained dog (the dog will immediately sense the different smell). [Answer] Rigor mortise sets in immediately with this alien biology. The muscles loosening up is a uniquely earth-bound biological mechanism. No need to posit that it HAS to happen with aliens. Their muscles could immediately stiffen, due to the enzymes that allow the extreme flexibility of the muscles no longer being effective in death. The enzymes are no longer biologically active, the muscles immediately freeze up. Since I assume the Ko'dor have no bones, I can't see any particular necessity for them to return to their 'natural' shape. [Answer] Ko’dor's body is like a piece of paper, and their assumed forms are like origami figures. Even after they die, they stay in their latest shape. [![enter image description here](https://i.stack.imgur.com/QvQ6W.jpg)](https://i.stack.imgur.com/QvQ6W.jpg) [Answer] Why not have no one see the corpse? Your spaceship just stayed on a planet where a contagious disease has spread. When the alien dies, his health monitor detects the death, but is unable to determine what caused it. So the disease is suspected, the corpse is handled by robots, frozen and send in the morgue, in an airtight coffin, to be autopsied when the spaceship reaches the next planet. The robots may detect that the corpse is not human, but they're not programmed to alert the crew in this situation. ]
[Question] [ Hello everyone! I've been sitting here for the past hour extensively rewriting a setting because I ran into an issue with mapping. I had a setting built off the good 'ol concept of a dyson sphere world. By this I specifically mean, a world on the inside of a dyson sphere, similar to an inverted world. But when I was mapping the size of the world it got out of hand, even using a blue dwarf or similarly "minimal sized star". The sphere encompassing the star was just beyond the realms of reasonable for the size of world I want to work with, as I plan on detailing much of the land masses. So I'm kicking around the idea of using a neutron, pulsar, or magnetar as the size of those work perfectly for what I have planned. I have figured out a way to explain away the whole radiation killing everything and magnetic field killing everything and temperature being far outside the realms of any sort of livable condition in a somewhat believable way. But I can't get past this whole "hundred billion times normal gravity thing" and was wondering if anyone knew any concepts I should explore in search of a solution to this issue. Currently, everyone would simply fall into the sun and the sphere would implode under that amount of gravity. Fantastical concepts are fair play, this is in a science-fantasy world with elder space gods & other good stuff. I'm just trying to figure out gravity nullification concepts for this, if it's even possible. I've already considered several ideas and done a good bit of preliminary research such as standard anti-gravity fields and the concept of rotating at a high speed to counteract the gravity, but nothing showed up on nullifying something with gravity this intense. I'm looking for suggestions on ways to explain the idea of nullifying the gravity of a neutron star in a semi-believable way. [Answer] This has been pretty well covered in the comments on your question by @Renan and @Otto Abnormalverbraucher, so credit where credit is due, but I thought it deserved its own answer. Net gravitational force in a spherical shell is 0 This is a well established [concept](http://hyperphysics.phy-astr.gsu.edu/hbase/Mechanics/sphshell2.html) in physics. At any point inside a spherical shell (which your Dyson sphere is), one will feel no gravitational attraction to the inner surface of the shell. Give it a whirl One way to simulate gravity inside the Dyson sphere is to spin it to create centrifugal "force." This will create a sensation of gravity towards the inner surface. The simulated gravity will be weakest where the axis of rotation meets the Dyson sphere (poles), and strongest at points furthers from the axis of rotation (equator). Sharing space If you want gravity in your inverted world you will need spin (presuming you don't handwave this). If you also share space in the Dyson sphere with a neutron star, you can counteract the gravity of the star by increasing the spin to counter that. Note that you will have major differences across the inner surface. If traveling from the "equator" (where gravity is outward towards the Dyson sphere) towards the "poles" (where gravity is inward towards the neutron star), one would eventually reach a point where the gravity shifts from outward to inward and fall into the star. [Answer] You want to build a dyson sphere around a neutron star and you want to devise ways to neutralize its strong gravitation. Presumably, because high gravity will make life extremely uncomfortable for the inhabitants of the dyson sphere. This answer will suggest two things. One, you need to rethink your dyson sphere, but only slightly. Two, forget about gravitational nullification because it's not at all necessary. Instead of living on the inside of the dyson sphere its inhabitants can live on its outside. If the surface of the dyson sphere is at the correct distance from the surface of the neutron star it will have a surface gravity of one gee. This is same amount of gravity as found on the surface of good old planet Earth. Also, the dyson sphere will act as a shield to radiation and intense magnetic fields surrounding the neutron star. This type of dyson sphere has been modelled for white dwarf stars. To use a neutron star as the primary gravitating body around which a dyson sphere can be constructed is but a step up. The relevant paper is [Dyson Spheres around White Dwarfs](https://arxiv.org/abs/1503.04376) (2015). Its authors are Ibrahim Semiz and Salim Ogur. Copies can be downloaded from the link above. > > We point out that Dyson Spheres could also be built around white dwarfs. This type would avoid the need for artificial gravity technology, in contrast to the AU-scale Dyson Spheres. In fact, we show that parameters can be found to build Dyson Spheres suitable --temperature- and gravity-wise-- for human habitation. > > > Obviously building a dyson sphere a neutron star will technically more difficult to accomplish than building one around a white dwarf. But it is reasonable to assume that technology will advance to the point that doing the same for neutron stars to become feasible. A neutron star dyson sphere will not need either artificial gravity technology or gravity nullification technology. The dyson sphere only needs to be built at the correct distance from the neutron star where the effective gravity will be one gee. In conclusion, this answer argues for the proposition that while the querent believes that gravity nullification is necessary for a neutron star dyson star, this isn't needed at all. [Answer] I don't think this idea would work too well because tidal forces (difference in gravity with respect to distance) around neutron stars are very strong, so if the Dyson sphere got out of balance the increased gravity on one edge would be catastrophic. If you had some very powerful ion rockets they could maybe ensure stability (can't remember the novel where I first read this idea). ]
[Question] [ Idea prompted by Brian Greene's The Elegant Universe: String theory postulates microscopic dimensions in space. Could you conceal an object by rotating it into one of the microscopic dimensions and then retrieve it by rotating it out of it? What would that be like? How would I describe it? [Answer] The problem with [the compactified dimensions described in that book](https://en.wikipedia.org/wiki/Compactification_(physics)#Compactification_in_string_theory) is that they're way too tiny. Greene's extra dimensions are as small as one Planck length, and the macroscopic objects are as large as one Planck length in thickness in each dimension. So, you can't hide anything by rotating it through the other dimensions, any more than you can hide a 1cm-thick rope by rotating it around its axis. However, with the later [ADD1 theory](https://en.wikipedia.org/wiki/Large_extra_dimension), where the fundamental scale is as low as the weak scale, some of the compactified dimensions are more on the order of 1mm, while the thickness of most objects is still down near the Planck scale. This is an easy way to get braneworld physics. For example, with 3+1 normal dimensions, 2 large extra dimensions around 1mm, and 4 tiny extra dimensions around the Planck length, you can have multiple 3+1 universes constrained to 3+1 branes, that are almost entirely independent of each other, but still interact via gravity—which falls off as `r^4` instead of `r^2` across the compact dimensions, making a difference small enough to not invalidate all of our previous experiments2 but just large enough to make a difference. In that case, rotating an object through one of the large extra dimensions would essentially mean moving into the empty space between branes in the multiverse. A tiny rotation (even near the Planck scale) would be enough to make an object invisible to electromagnetism (and the strong and weak forces). But, with sensitive enough detectors, it could still see our universe's very pale gravitational shadow, and vice-versa. And meanwhile, if our brane is sandwiched between two other branes, rotating could mean making contact with a whole other universe, possibly filled with weird and dangerous aliens, who maybe even live according to slightly different laws of physics. Which opens the door to all kinds of spare-opera plot devices. --- The big problem is how you get the force to push or pull an object on those axes. EM, weak, and strong forces can't propagate in those directions. Gravity can, but any reasonable gravity (or anti-grav magic) would be likely to push you much harder along the brane than it would off-brane. Your best bet there would be to not describe how it works. Keep your pseudoscience technobabble less specific than Star Trek. Maybe mention helicity or twist and leave it at that.3 As for what it would be like for people watching objects pushed out of our universe—they just vanish. One microsecond they're reflecting light, the next they aren't. And the same goes for people inside spaceships or other objects that get pushed out of our universe—all of the light from stars and galaxies, or reflected off close objects, just disappears instantly.4 --- 1. Named for its inventors, Nima Arkani-Hamed, Savas Dimopoulos, and Gia Dvali. 2. Unfortunately, LHC experiments and neutron star observations done since then to measure mm-scale gravitational effects seem to rule out the original ADD model. Of course you can adjust things and come up with a new theory that's still compatible with all of the results, but many of the original motivations for ADD are no longer so compelling, so not much work is being done there. 3. Around the turn of the century, it was popular to throw in the term [Calabi-Yau manifold](https://en.wikipedia.org/wiki/Calabi%E2%80%93Yau_manifold#Applications_in_superstring_theory), and most readers would just assume you know more physics than them, instead of less. I'm not sure if that still works a couple decades in; maybe better to just say "superstring" or "D-brane". 4. At least far faster than a human could possibly detect. If you have super-fast AIs and want to try to describe their perceptions, maybe they see it quickly fade out. But they're probably also directly experiencing those "gravity shadow sensors", right? So, they see gravity shadows receding at r^4 instead of r^2, like everything in the universe is becoming quadratically more distant, which is probably a more interesting distortion t describe. ]
[Question] [ A civilization of land-living humanoids occupies a patch of land on a continent (patch of land size: a few US States, let's say Montanas) and, without even exploring the continent fully, develops space travel and starts to explore space. Their home planet is similar to Earth, fully habitable, with a number of continents, oceans, etc. There are other races on the planet, some of them have civilizations, but they are much more primitive. What I need is a reason, why exactly would they not explore their own homeworld, rather choosing to expand in space? [Answer] I want to ask for caution, before presenting a possible scenario: Space travel is not something a civilisation would develop in short time. This likely requires centuries for a single civilisation, if not millennia (and several cultures and civilisations), as it did on Earth. During that time, your people will likely not sit still, focusing on developing astrophysics and quantum mechanics, while they could use ships or later airplanes (which are a reasonable intermediate step between land and space travel) to reach other continents far more easily than reaching space. However, humanity as we know has developed space travel, while vast amounts of our planet's surface are still undiscovered and a mystery namely the ones covered by oceans. This is not just the Mariana Trench, which is basically still out of reach for humans, even though we have already set foot on the moon forty-nine (49) years ago. High pressure is much harder to overcome than low pressure and there is simply not enough to gain from investing into such technology to drive its development as much as space travel. Thus, possible scenarios would be that your alternative races are descended from organisms, such as earthly archaeobacteria and thus adapted to either high pressure living far beneath the surface of the oceans or extreme heat and lack of oxygen, living within hot springs, liquid lava or whatever you like. Investing into a technology to move through lava streams, when you have the whole of outer space, has been clear decision for our scientific community and society and could also be so for your fictive society. [Answer] They want satellites. These folks are not much for showing up in person. They are fond of their neighbors, but as you get farther out of town stuff gets weirder. Folks smell like strange spices and look at you funny. And the outside world is full of one eyed cannibal people and giant spiders and is not a place for civilized peaceable folk. These people are homebodies. But they very much like their shows and being in virtual touch with one another! Radio towers have their limitations and balloon towers get blown down by storms. A geostationary satellite or two would be above the weather and do very well covering their land with broadcast shows and satellite phone. Once they get a satellite up there with camera capability it confirms their fears about the neighboring countries - chock full of monsters and maniacs. But they start to wonder - are there some places farther out that might lack scary stuff and fierce people? Maybe the moon? Maybe a satellite around the moon could check it out remotely. So it begins. [Answer] Your humanoids are the indigenous species of a planet which was colonized by aliens prior to your own industrial and technological revolutions. Imagine if alien traders had landed on Earth during the Middle Ages, prior to the European discovery of the American continents. If those traders were not governed by a Prime Directive, King Henry IV (no relation) might have found himself in possession of an FTL space ship to complement his fleet of wooden-masted sailing vessels. [Answer] Primitive doesn't mean they're not dangerous. The other races may be a match for yours, despite the massive technological advantage, because they have evolved a body which is better for such combat. A classic example would be the Eldar vs. Orc in Warhamer 40k. The Eldar and Orc are evenly matched because the Eldar are physically frail but have great technology. There are also issues with the small number of Eldar remaining, vs the Orcs which reproduce like... well... they make rabbits look lazy. Or your opponents simply could have studied war better than you. Consider the case of the [finale of V for Vendetta](https://www.youtube.com/watch?v=8WZ0XSf23rs), which includes one of my favorite lines: > > Creedy: Bollocks. Whatchya gonna do, huh? We've swept this place. You've got nothing. Nothing but your bloody knives and your fancy karate gimmicks. We have guns. > > > V: No, what you have are bullets, and the hope that when your guns are empty I'm no longer be standing, because if I am you'll all be dead before you've reloaded. > > > There are plenty of reasons to need to respect a primitive adversary. Even the Marines and the SEALS respect the snake, and take care to ensure they don't disturb one. A cottonmouth can kill, even with all our technologies. [Answer] This question keeps me thinking. Logically your species fulfills all premises for a sucessful colonization of your planet: * Your planet is habitable, which means cliamte and temperature won't hinder exploration * Your planet has enough land to settle on (so not an ocean planet with a single, small island) * The other species aren't as highly developed, so it should be easy to 'dispose of them' * your species is in the era of space-flight, which means they should able to travel easily around the planet * Since they try to explore space they have to have at least some kind of curiosity. But the hardest argument against having a "not fully explored planet" is probably * if they have space-travel-technology, they are also able to build sattelites, which would make it quite easy to explore the planet from space. I've thought about a few reasons they might've chosen not to explore their planet * *The nations of your species are constantly at war.* Even though there are only primitives, putting aside valuable resources and manpower to expand on the own planet can break the balance between the warring nations. * *Your species is pacifist, even though they'd like to expand, they just can't hurt any of the primitives, while they have no problem hurting them. So they look for an unhabitated planet somehwere else *religious or personal believes have stopped your species from expanding on their own planet.* Guess it won't be some kind of "we'll fall off the edge of the world" logic, but maybe they fear of going to hell if they die outside of the 'holy land' (although I didn't find a valuable explanation why spacetravel would be ok tho), or don't want to interfere in the eco-system. * *economic reasons.* Our world is overpopulated and global warming is an immnent thread. Maybe your civilization tries to reduce the damage they do on their own planet by restricting their habitat to a minimum. * *They depend on a plant, which grows only in very specific conditions.* Since you said your whole planet is habitable this plant shouldn't be food, but maybe a quite powerful drug. Withdrawal will drive you crazy or even kill you. * *Its just not worth it.* It is hard to come up with reasons, why settling on habitable ground with very little resistance shouldn't be 'worth it', but maybe your planet has a lot of seismic activity and your people live on the only tectonic plate, that's spared of constant earthquakes. Your species might live in a different altitude (in a hole or on a mountain range like himalaya), so breathing on 'ground level' isn't really possible. Maybe your species isn't as advanced in any other sector as in space flight. They have no ships, no cars, maybe no medicine to handle all the different illnesses in other places. # Conclusion I can come up with quite a few reasons why they didn't settle anywhere else, but it is quite hard to explain why they shouldn't have explored their planet at least to the same extend we have, when they are able to build sattelites. ]
[Question] [ As a follow up question to [Could dinosaurs survive in today's environment?](https://worldbuilding.stackexchange.com/questions/17685/could-dinosaurs-survive-in-todays-environment) I was wondering which dinosaur would have the highest chance of survival if it was brought back to life today and left alone in some natural reserve with no human interaction. As was discussed in the previous post, large dinosaurs would probably struggle to find enough food on a daily basis. Many herbivores would find current plants inedible or poisonous. I was thinking the best candidates would be small,carnivorous or insect eating dinosaurs but I might be completely wrong . [Answer] There are plenty of dinosaurs around yet, normally referred to as "birds". Cretaceous and Jurassic dinosaurs that are similar to modern birds could likely get by. I don't know that modern plants would be bad to eat, nor do I have a clue how to verify such a thing. There would be modern plants that are poisonous to the dinosaurs, presumably, and the dinosaur you just time-traveled or cloned won't have evolved avoiding those plants. If most plants are inedible or poisonous, why would modern animals be nourishing? [Answer] I would personally still imagine it to be a small to medium sized Herbivore that would be the most stable. While you bring up the idea that current plants might be inedible or poisonous you can't just rule it out. There is a reason herbivores were so successful that something evolved to eat them in the first place. Firstly Herbivores don't need to rely on another creature for their food supply. Its the sun and plants. Being at the bottom of the food chain means they have a more reliable source of food. Other creatures that eat meat wouldn't survive if the plants and sun went away either because their food sources also dies out eventually. If a herbivore can't survive in a certain area because of lack of plants, no creature that relies on herbivores will be able to survive in the same area. How for size, large is basically out of the question. They would need to roam around and eat a huge supply of food. Chances are their old food supply and the reason they evolved so large in the first place is now gone and so they are going to have a tough time finding a replacement. Your smaller and medium sized herbivores are going to have more luck on the ground finding plants that are similar to what they ate before and the correct size. I would go with medium over small because size offers a bit more protection from predators but it really depends. Of course for the the actual dinosaur, I'm just going to say Triceratops. Why? Because the only other herbivore dinosaur I know is the Stegosaurus and the Triceratops is cooler. [Answer] I'd say adaptability is a significant factor in survivability, so i'm looking for a dinosaur that is able to easily migrate over large distances. For that reason my money is on a large Pterosaur, such as Tropeognathus Mesembrinus. The larger species would most likely have the greater range. These creatures were believed to be the kings of the skies, and appear to have found their food in the seas and lakes. Considering the other creatures around today I think this position would remain unchallenged! They would likely be vulnerable to predators when grounded, but with a significant estimated flight range they would have had the luxury of being able to island hop and select a habitat that suits them, being able to nest on the most inaccessible clifftop, or even mountaintops, and venture further out to sea than most in search of food. [Answer] For a dinosaur to survive, you would want to keep it in a zoo. This means it should not be too big, so it can be captured and contained easily. This means a small territory needs would increase its odds of being in a zoo. Being an herbivore might decrease its lifespan considerably, because of toxins in plants that did not exist in its time. This means that it would have to be a [theropod](https://en.wikipedia.org/wiki/Theropoda) (correct me if I'm wrong), and an omnivorous one might work the best because it has the least restrictions on food. I would suggest the [oviraptor](https://en.wikipedia.org/wiki/Oviraptor), because they only get to 5 feet in height, which makes them less dangerous to catch and cheaper to feed. They had beaks that can crush bones, so more foods, especially ones that humans cannot eat are options for them. I may be misinterpreting the question, and living in zoos is not the focus, and in that case, oviraptors are not a bad choice. They are faster than most wolves, at a top speed of 43 mph, but their diet size is limited because they are not pack hunters. They can still hunt rabbits, and wild turkeys Also, they may be able to get into bird farms and eat the birds. [Answer] Nothosaurs and pliosaurs aren't dinosaurs... They are aquatic reptiles and quite far away from any dinosaur. Dinosaurs are restricted to land areas and never occur in water. Pterosaurs aren't dinosaurs, too... They are flying reptiles and no dinosaurs! Dinosaurs are characterized by the appearance of an antorbital foramen and two temporal skull openings... Neither aquatic reptiles nor flying reptiles show these autapomorphies. Speaking for dinosaurs, small herbivorous forms like Hypsilophodon foxi would have the best chance to survive... All big forms like sauropods would nowadays starve because we don't have any forests big enough to hold herds of these animals... Small carnivorous theropods might also have a chance... They don't need that much food to survive and hunt in packs. Big theropods like T rex need too much food and would starve, too. Armored dinosaurs like Stegosaurus and Ankylosaurus are quite nice, but their potential ecological niche (savanna like landscapes) is totally crowded with big herbivorous mammals. Same applies for Parasaurolophus and other herbivorous herd-building dinosaurs. [Answer] # Nomenclature Ignoring the "bird" solution (while birds are the closest descendants of dinosaurs, it stretches the English language excessively to say that they really are dinosaurs in the same way that it stretches the English language to say that humans are chimpanzees), the dinosaurs most likely to manage if revived would be aquatic dinosaurs. Technically, they are "marine reptile megafauna" rather than true dinosaurs, but they fit the general sense of the word dinosaur better than birds do. # Two candidates [![enter image description here](https://i.stack.imgur.com/kQ204.jpg)](https://i.stack.imgur.com/kQ204.jpg) [Pliosauroids](https://en.wikipedia.org/wiki/Pliosauroidea) (illustration above per Wikipedia), which had large heads with very strong jaws and short necks, inhabited an ecological niche similar to large sharks, would be one strong candidate. [![enter image description here](https://i.stack.imgur.com/QGU48.jpg)](https://i.stack.imgur.com/QGU48.jpg) [Nothosaurs](https://en.wikipedia.org/wiki/Nothosaur) (illustration above via Wikipedia), which inhabited a ecological niche similar to seals, would be another. # Analysis The blue sea environment is probably the most similar today to what it was in the era of the dinosaurs of any ecosystem on Earth. Both the flora and fauna of terrestrial Earth are mostly dramatically different from what they were in the dinosaur era, but the blue seas and oceans of today are far more similar to what they were like then, and will become even more similar with global warming. There are lots of marine species that are still undiscovered and there are other "living fossils" like the coelacanth that were thought to be extinct only to be recently rediscovered, so these species might be discovered long after they were reintroduced. ]
[Question] [ In my sci-fi universe (The same as my [first question](https://worldbuilding.stackexchange.com/q/114529/44516)) it is common throughout the asteroid belt to 'Bump' (somehow cut off and then shove a ship off of an asteroid) miners. Usually this is only done to small scale mining operations that haven't established much on the surface of the asteroid (so they can bump the ship and then re purpose the basic mines they built) In Warlords (The universe name) ships are usually tied down to asteroids by large re purposed docking cables that are drilled into the Asteroid to ancher the ship. To actually mine the miners use either exo-craft or space walk to the surface of the asteroid to establish the first searcher tunnels on the Asteroid. Now the part that I'm actually stuck on is the 'how'. I've gotten to the simple 'Cut the cables', but how would you then shove the ship away from the Asteroid? Also for bonus points: Is there any way that you could 'Bump' a ship without severely crippling the ship (So they can limp away and not become a liability), destroying it, or killing the crew (both of these would create a scene most likely)? Note: Most ships make use of Ion drives normally supplemented or working with Fusion Reactors (the fuel for these I'm still trying to figure out, but He3 seems like a good idea). Finally for quick bursts of speed plasma propulsion using H3 is used. Ship sizes are usually pretty large (In my mind) for mining ships usually having a large family (20-30 individuals) as the basic crew. Being around 100-200 meters in length for the average mining vessel. I had a ship looking something like this in mind: [![Desired appearance for armed mining ship](https://i.stack.imgur.com/SnrmQ.jpg)](https://i.stack.imgur.com/SnrmQ.jpg) Image by [Kevin Massey](https://kevinmassey.deviantart.com/art/Allied-Enemies-ROW-Faction-Battleship-411880448). PS: I'm going to put the science based tag for now because I want a realistic answer to the bumping question (but I don't want someone to spend hours crunching the numbers) [Answer] Just bump them! After you have severed the cables - since asteroid gravity is negligible - even the tiniest thrust is enough to accelerate the victim ship away. So you approach slow (say 1m/s) that the collision is not too destructive, and upon contact, you fire up (slowly) your engines to push the other ship away. Even if the victim has superior thrust, with carefull manouvering you can hit it in the side, so it can not 'bump back'. Or if you do not want to scratch the paint on your ship's nose, you can fire on them low velocity, non-rigid slugs or missiles to push them away. EDIT: On crippling/not crippling victim ship by side bumping Sadly I dont think there will be repeated counter bumping. In space every gramm counts. So non-military vessels will have much more acceleration tolerance in the thrust axis of their main engines than in any other direction. Like [these](http://www.projectrho.com/public_html/rocket/realdesigns.php). This means that if you manage to hit your victim in the side, they are at your mercy. If you are sure that they will get the message (that you are the big guy on this rock, and that they better leave) you would just bump them gently (just the acceleration needed to overhelm their RCS thrusters), but if you are the weaker and more desperate party, you will use full acceleration, severing their load-bearing structure with the non-planed-for acceleration (and perhaps throwing them sideways from their crash chouces, breaking propellant feed lines, etc...) leaving them crippled and waiting for rescue. [Answer] I love a quote from Star Trek VI: The Undiscovered Country: > > The thing must have a tailpipe! > > > Recapture a portion of the gaseous output of your own engines to be used pneumatically — in other words, give them an air blast! ``` The AstroConquerer class mining vessel model XN1-37748 comes standard with the patented Halstrom EGR system with convenient distribution points on the hull for blowing off dust and debris accumulated during the mining process. ``` "And with a few extra pipes, it's useful for blowing 'dust and debris' off our asteroid, eh Johnny?" [Answer] Malicious Hacking Your crew of skulduggerous miners use malicious hacking to hijack the ship and get it to shove off on it's own. Or maybe they use this access to the opposing ship's computers to generate a false alarm regarding asteroid instability, or a dangerous incoming solar storm to ensure that the opposing crew are all shacked up in radiation shelters when they use an alternate physical method to shove the enemy ship out of the way. I particularly like the idea b. Lorentz suggested in one of the comments that utilizes a pneumatic sand-bag cannon. But Why? I think a bigger question that needs answered is why competition over these space rocks is so heated. It is estimated that over 150,000,000 asteroids 100 meters in diameter or larger are present in our solar system. Whats in these asteroids that is so valuable its worth risky maneuvers and violent competition to gather them? Nickel and Iron are not exactly going to be at a premium in a society with access to literally hundreds of millions of potential mines for such materials. [Answer] Sapper-Miner. <https://en.wikipedia.org/wiki/Sapper#Miner> > > The saps (combat trenches) permitted cannon to be brought into firing range of the > besieged fort and its cannon, but often the cannon themselves were > unable to breach the fort walls. The engineers would dig a tunnel from > the forward-most sap up to and under the fort wall, then place a > charge of gunpowder and ignite it, causing a tremendous explosion that > would destroy the wall... > > > So too on the asteroid. A rival group digs a mine under the undesirable ship and sets off an explosive. This explosive cracks off the hunk of stone the ship is moored to, and also serves as the impetus to put the whole thing (asteroid fragment and ship) in motion out and away from the asteroid in question. With a little luck the inhabitants of said bumped ship might not know they were bumped until they venture out. Mooring cables are all intact. Relative position to asteroid unchanged. Their asteroid has just become very small. ]
[Question] [ Life had been good for a certain class of tetrapods. They evolved two layers graphene in a specialized collagen creating a relatively thin yet seemingly impenetrable hide. All of their natural predators moved on to other prey without such tough skin, but soon over competition for plants struck. Many of them remained herbivores, but in order for many members of this class to survive, carnivory had to evolve again. It would be difficult, but probably not impossible, as no creature could truly make perfect graphene. Perhaps small flaws in the collagen itself could be exploited. The collagen not only contains graphene, but also copper to support its structure. Both copper and carbon are a major and plentiful part of the diet for these tetrapods. I am mainly concerned about the required materials to damage the graphene. Would they be biologically attainable and maintainable? I omit to go in depth about the structure of the collagen so that liberties can be taken. After all, if the graphene collagen were too difficult to damage, the tetrapods would have faced mass extinction due to overpopulation. As a basis, currently, the creatures are constructed with the same elements animal life on Earth is, but in different concentrations. There is more copper than there is on Earth, but many animals use hemoglobin in their blood, plus iron in their bones. I am always interested in hearing about new elements to incorporate in their biology, so if anything else would be helpful, it would be great to know. So far, I have pictured mostly teeth and/or claws, as those weapons seem to work very well for predators on Earth. In the end it comes down to whatever can get the job done (as long as the predator still has a good chance of being alive afterwards.) [Answer] *Attack what inside* and what is exposed. No matter how you skin your creature it's going to suffer just as much from impact damage (think e.g. broken bones) and things like suffocation or crushing. In addition shock waves from impacts will still travel through the body and cause damage. In this regard consider the effect of a nearby shell burst to a human which does not cause any exterior sign of injury. It can still rupture internal organs as a result of the shock wave and kill in moments. An animal can blind you either temporarily or permanently. Deafen you. Simply immobilize you. Eventually you starve to death. Drag you to e.g. water and drown you. I can heat you. Even if your skin is intact, the heat will cause damage internally and most creatures can be killed by heat (or lack of it) pretty quickly. Poison. Always a good choice. > > I am mainly concerned about the required materials to damage the graphene. Would they be biologically attainable and maintainable? > > > I'm not at all clear how your creature can biologically create graphene. It's not a process I can see being produced in nature. My (limited) understanding is that graphene is brittle, especially when impure and is also prone to edge fracture (and somewhere there will be an edge). By comparison methods of imparting high impact, crushing, suffocation and so on are innumerable. Nothing special required. > > iron in their bones > > > This achieves what I wonder ? My knowledge of alloys is limited, but I can't think of a particular advantage of mixing iron and calcium. I think you might need to read up on the [complex structure that is typical animal bone](https://en.wikipedia.org/wiki/Bone). [Answer] Eat the whole thing. If you have an impenetrable shell, that will not help if you are eaten in your entirety. Eventually your shell will open, or your digested substance will come out through your eye holes. This is the method gray whales use on clams. [![gray whale feeding on bottom sediment](https://i.stack.imgur.com/QCsRD.jpg)](https://i.stack.imgur.com/QCsRD.jpg) <https://www.arkive.org/gray-whale/eschrichtius-robustus/video-08a.html> > > This species is the only cetacean to feed by straining the sediment on > the sea floor. Individuals roll onto their sides after diving to the > bottom and take large amounts of sediment into their mouth. As the > whale rises to the surface it strains the contents of the mouth > through the baleen, leaving a trail of mud and sand behind it. The > invertebrate prey consisting of bottom-dwelling crustaceans, worms and > molluscs is isolated in this way and swallowed. > > > So too your creature. Its predator eats it in its entirety. Maybe the predator is much larger, as a whale is larger than a clam. Or maybe the predator has an expansile stomach like a gulper eel or anaconda. In any case - in it goes and then time and enzymes do the rest. The untouched graphene skin might be retrieved from the feces of this predator. [Answer] When people talk about Graphene being strong, they often forget that there are many different types of strengths. The strength of macroscopic materials also are highly dependent on the [lack or presence of defects](https://physicsworld.com/a/graphene-has-record-breaking-strength/). Graphene with defects only has about 4% the strength of pristine graphene. Typically small samples of graphene are tested. The weakness of graphene will be in small defects. Well it turns out graphene is [actually kinda brittle.](https://www.livescience.com/45216-graphene-weak-link-discovered.html) There is a good chance that the skin of your tetrapods at the joints, and other flexible points will have many cracks. Predators would eventually learn to go for those joints. However, if you don't like that, you could just have the graphene skin be impenetrable. It does not mean that they would go extinct from over population. Many species do not have natural predators and other environmental pressures can keep their population in check (such as limited food supply). However, there is another route you can take. [Graphene can react chemically](https://en.wikipedia.org/wiki/Graphene_chemistry) (though for the most part it requires defect sites to do so). If a predator could oxide some of the graphene skin (such as if it had evolved a way to produce a mixture of sulfuric acid H2SO4, sodium nitrate NaNO3, and potassium permanganate KMnO, or something similar), it could spray it on the skin. Once graphene become oxized, it is easily permeable by water (and I am assuming blood), and your tetrapod would bleed out through its skin. [Answer] ## Tasers Graphene is an excellent conductor of electricity. Getting hit with a taser would be devastating because the impact would not be localized between the impact points as it is in humans and would instead spread across the whole body and in extreme cases, cook the organism inside. [Answer] Option 1 Graphene is essentially pure carbon, several carbon atoms arranged in an hexagonal pattern on a plane. Carbon is well known for its eagerness to oxidation, and the lack of any other atomic species around make it just easier for the chemical reaction to start. So my guess would be that any attack based on oxidative species (oxygen, halogen gases, etc.) would have good chances of being successful at damaging the graphene skin. Option 2** Another possible direction is the usually played games of evolution: when a defense gets better, the offense improves, too. Graphene, like diamond or rubber, can be good against 1 particular attack, but can be vulnerable to others. It's just a matter of exploiting it. Take porcupines, for example. They might look tough to attack, yet [some predators have learned](https://outdoors.stackexchange.com/q/19435) that flipping them on their back gives access to a juicy lunch. For the case in discussion, if graphene can be developed by living organisms, nothing forbids that also predators can produce and use it in their jaws/claws. ]
[Question] [ First of all: I don't think that diamond is a good material to use. It isn't even really resistant to pressure. So... it's a stylistic choice and of course I want to know if nature could be this crazy. The "Creatures": The alien creature I'm talking about has a wasplike abdomen. All kinds of necessary fats and fluids are stored there. In the mid of it, there's also "the organ in which the babies grow". (This isn't easy for me) The "Baby": When the first growth process of the "baby" has ended, the "armor" gets added on its skin just before it gets spilled out. The "Process": Graphite gets around the "baby". It sticks on some places, on others it doesn't... [![1 minute paint sketch of scenario](https://i.stack.imgur.com/jXBwH.png)](https://i.stack.imgur.com/jXBwH.png) Some sort of hydrogen-gas-mixture is made hot through micro waves. (Somehow by another organ) The generated plasma turns the graphite into a layer of small diamonds. [![2 minutes paint sketch of scenario](https://i.stack.imgur.com/RWiur.png)](https://i.stack.imgur.com/RWiur.png) The Diamonds stay and are later used as armor, teeth and nails. [Source - Springer: "Diamond synthesis from methane-hydrogen-water mixed gas using a microwave plasma"](https://link.springer.com/article/10.1007/BF01153976) [Answer] Nature does not use the [Haber–Bosch](https://en.wikipedia.org/wiki/Haber_process) process (requires 400 C and 20 MPa) to produce ammonium, it uses [nitrogenase enzymes from rizobia bacteria](https://en.wikipedia.org/wiki/Root_nodule). Do the same: Make up a bacteria that can generate diamond, and have them live in symbiosis with your animal, in its skin. [Answer] You are running into the problem of Occam's Razor, aka Parsimony, and others... <https://simple.wikipedia.org/wiki/Occam%27s_razor> <https://evolution.berkeley.edu/evolibrary/article/phylogenetics_08> These ideas basically tells us that the path with the fewest steps, is that the path that is likely to happen. So the first problem is that to get to where you want this species to be you require so many contrived circumstances for a benefit that isn't even really that good (diamond skin?), that it is extremely unlikely to happen. It is not realistic, because if a real organism needed this amount of defense (diamond shell/skin) there is almost certainly a better, cheaper, more efficient, and more advantageous way to evolve a comparable benefit. For example if the problem is predators, have extremely dense bone? Be faster to not get caught? Etc. So you would need a ridiculous number of very specific circumstance to get to the point where what you have suggested could even be possible. But after it is, you still have problems with this species that would basically guarantee it dies immediately. For example what happens when the organism grows? Diamonds don't really expand to fit the shape of the growing animal underneath. So you have created an animal will likely go extinct in its first generation as it is crushed by developmental limitations, unfortunately. But this is not even the biggest problem. The biggest problem is the radiation. You're talking about having microwaves passing through this animals body that are so strong they turn gas in the womb into plasma. Nevermind the problem of containing plasma. Any animal that uses DNA will never be able to survive the radiation, or make a thriving species with that limitation. Any baby using a genetic coding system (even if it is different from dna) that can be destroyed by intense microwaves everywhere around them, microwaves that are strong enough to create plasma in its womb, would also have this coding system get destroyed. Think immense dna damage or even just have the rest of the animal turn to plasma too, why only in the womb and not all of its flesh? Regardless a baby that has to develop from a single cell or a small relatively unprotected embryo at some point in its developmental cycle will not survive any of this process. So is this realistic? It is not. Even in a crazy sci fi setting this is still not very realistic. But somehow somewhere if you think hard enough, there might be some way for this thing to exist. But you are looking at thousands of very specific environmental pressures. For this one you are probably going to need a lot of hand wavium. ]
[Question] [ I want to build a world where one planet could be visible from the sky, day and night with the naked eye periodically (like Earth's moon behavior) and not everywhere at the same time (since my world is a round-shaped planet too). My world would have a moon and a star/sun (both similar in relative size and distance of the Earth's). The visual I want for my world is similar as the background image of this StackExchange. I want a planet as visible as the big white planet in the sky. I'm wondering what could be the maximum size of the planet for it to have minimal impact on my planet. I'm looking for a way the planet would not have an impact on the day/night cycle or even too much impact on gravity (no apocalyptic event, minor events would be fine though) or even my world's climate. For now, I think that for the planet to have the minimal impact would be for it not to be between my world and my sun. I don't want my planet to hide the star but I don't want either for it to reflect the sun too much by night (the planet could have a color not as reflective as white ?) From there I want the planet to be as visible as possible for the creatures on my world. [Answer] Unfortunately, it is really hard to do what you ask. The specific thing you asked for in the comments is for the planet to be "bigger in the sky." You also mention the visual from the WorldBuilding page to be an example of the kind of planet you want to see. The trick is that those angular sizes are huge. Most planets are so small that they appear to be point sources until you look at them with a telescope. Jupiter, as large as it is physically, is only about 50 arcseconds wide [visually](https://blog.nationalgeographic.org/2011/10/28/jupiter-as-close-as-it-gets/). Now most people don't think in arc seconds, so to give you a sense of scale for that, the Moon is about 1,860 arcseconds wide. The [human eye](https://en.wikipedia.org/wiki/Naked_eye) can resolve objects who size is about 60 arcseconds, meaning objects larger than that appear to be "distributed" objects rather than point sources. This suggests that if you moved Jupiter closer, you could easily cross that threshold and people would see Jupiter as a circle rather than a point. However, if you want to move towards the scale of the moon, it gets trickier. If we pick an angular size (such as 1,860 arcseconds), then the radius of the planet scales linearly with the distance. So a planet 2x as far as the moon is from us would have to be 2x as big in radius to appear to be the same size. The mass goes up by the cube of this, so the mass of the planet would be 2x2x2 = 8 times more massive. The effects of gravity go down by the square of the distance, counteracting some of the mass. Thet net result of all of thes proportions? The gravitational impact of an object which appears to be a chosen size scales up linearly with the distance to the object. This has profound implications. Mars is at its closest about 55 million km from us. The moon is about 0.4 million km, so a Mars orbit is about 140 times further than that of a moon. This means that an an object that appears to have the radius of the moon would be approximately 100 times larger than the mass of Jupiter, and would have a gravitational effect of 140 times that of the moon. There's a reason that reasonably sized planets, like Jupiter, appear to be so small. For perspective for what this means, we could also look at the sun. The sun happens to be roughly the same size at the moon visually, which is why eclipses are such an exacting phenomena. This means that a planet 1AU away from your planet would literally have to be the size of the sun. So the solution is that if you want an object to be visible, but not have a major gravitational effect, you want it to be closer. What you really want is a smaller closer moon, which appears bigger but has a smaller gravitational impact. If your object needs to be planet sized, it simply gets tricky to make that a reality. [Answer] According to this List of Exoplanet Extremes: <https://en.wikipedia.org/wiki/List_of_exoplanet_extremes>[1](https://en.wikipedia.org/wiki/List_of_exoplanet_extremes) The planets Kepler-70b and Kepler-70c approach each other to a distance of about 240,000 kilometers, and when they are at the closest approach, Kepler-70c would appear 5 times the size of the Moon in Kepler-70b's sky. But from what I see they are unlikely to be habitable planets. <https://en.wikipedia.org/wiki/Kepler-70>[2](https://en.wikipedia.org/wiki/Kepler-70) From what I have read the potentially habitable planet with the shortest year is TRAPPIST-1d with a year 4.05 Earth Days long. <https://en.wikipedia.org/wiki/List_of_potentially_habitable_exoplanets>[3](https://en.wikipedia.org/wiki/List_of_potentially_habitable_exoplanets) TRAPPIST-1E at closest approach to TRAPPIST-1d would be about 2.731 times as far as the Moon is from Earth, and has 0.91 the radius of the Earth. The Moon has a radius of 0.273 the radius of Earth, so TRAPPIST-1E has 3.333 times the radius of the Moon. At it's closest approach TRAPPIST-1E would appear 1.220 times as wide as the Moon from TRAPPIST-1d, though at other times it would look much smaller than the Moon. <https://en.wikipedia.org/wiki/TRAPPIST-1#/media/File:PIA22094-TRAPPIST-1-PlanetLineup-20180205.jpg>[4](https://en.wikipedia.org/wiki/TRAPPIST-1#/media/File:PIA22094-TRAPPIST-1-PlanetLineup-20180205.jpg) So this example shows that it is possible for a potentially habitable planet to sometimes get close enough to another planet in its solar system to see that other planet at least as large as the moon looks from Earth. But if you want a situation where the other planet looks much larger than the moon from the surface of the habitable planet you will have to get someone else to construct your solar system and do the calculations. Another possibility is a habitable planet in a Trojan orbit with a gas giant planet and a star. If the star is a really dim red dwarf the habitable planet would have to orbit very close to the star. Thus the orbit of the habitable planet would be a relatively small one and the 60 degrees of separation between the gas giant planet and the habitable planet would be a relatively small distance. If the habitable planet and the gas giant planet orbit at 10,000,000 kilometers from the star, the two planets in a Trojan relationship would be about that far from each other. At that distance a gas giant the size of Jupiter would have an angular size of about 0.75 degrees or 45 arc seconds, about 1.5 times the angular diameter of the moon as seen from Earth. The smaller, habitable planet would actually move a lot around the exact L4 or L5 position, and would get significantly farther and closer to the gas giant planet, making it appear sometimes smaller and sometimes larger than calculated. Since TRAPPIST-1d is in the stellar habitable zone and orbits TRAPPIST-1 at only 3,330,000 kilometers, a habitable planet could be a third as far from its star as in the Trojan system above. Thus if the gas giant is as large as Jupiter it could appear 4.5 times as wide as the moon from the habitable planet in the Trojan position. Unfortunately Jupiter is almost as large as the largest possible gas giant. Gas giant planets much more massive than Jupiter are believed to have smaller diameters as their intense gravity compresses their atmospheres. Another possibility for a planet appearing very large as seen from a habitable planet would be a hot Jupiter. Hot Jupiters are gas giant planets orbiting very close to their stars and having very high temperatures, hundreds or thousands of degrees hotter than Earth. Some hot Jupiters are called "puffy planets" or "hot Saturns" because they are very large and have very low density. They are so hot that their atmospheres swell up and their diameters increase. WASP-17b, the puffiest known planet, has about twice the diameter of Jupiter and half of it's mass. Unfortunately, a habitable planet would have to orbit their star several times the distance of the hot Jupiter in order to have habitable temperatures. Thus their star would have to be a very dim one for their orbital separation to be only a few million kilometers. And the hot Jupiter would look the largest when it was between the habitable planet and the star and thus would look like a very thin crescent during the day. Also you might want to check out this: <https://planetplanet.net/2017/05/03/the-ultimate-engineered-solar-system/>[5](https://planetplanet.net/2017/05/03/the-ultimate-engineered-solar-system/) And ask about calculating to make the distances between planets as small as possible. Thus my calculations indicate that it would be difficult to get another planet to appear more than a few times the apparent diameter of the Moon in the sky of a habitable planet. Possibly someone else can suggest a plausible orbital arrangement to make another planet look much larger. But if the habitable world is not a planet but a hypothetical Earth-sized moon of a gas giant planet orbiting in the habitable zone of their star, the gas giant can appear quite large in the sky of the habitable moon. And other large moons would appear to get larger and smaller as they orbited the planet. There are, of course, some limitations on the maximum and minimum apparent diameters of gas giant planets as seen from any habitable moons they may have. If the planet has a diameter between those of Neptune and Jupiter, for example, the planet's apparent diameter as seen from a moon at a specified distance would be between those of Neptune and Jupiter at that distance. And depending on the mass of the planet and the mass and distance of the star, there are inner and outer limits for the orbit of habitable moons. <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3549631/3>[6](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3549631/3) [Can a gas giant have its own habitable zone?](https://worldbuilding.stackexchange.com/questions/6909/can-a-gas-giant-have-its-own-habitable-zone/107174#107174)[7](https://worldbuilding.stackexchange.com/questions/6909/can-a-gas-giant-have-its-own-habitable-zone/107174#107174) [Answer] Here are couple views of Jupiter from its moons, and they do look like the background image. <https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA17043> <http://www.spacetelescope.org/products/art/frank_hettick_1/> They are simulated images, but made by space agencies, so I hope they got the scale right. I know you wanted your planet to have its own moon, but it is [apparently not very likely](https://medium.com/starts-with-a-bang/can-moons-have-their-own-moons-ff674a35a4ba) if your planet is a moon of a gas giant. You will have view of other moons, though. Btw, if you really get two similarly-sized planets close together, they can get tidally locked, so the neighboring planet will be in the same spot in the sky, and you will not be able to see it from half of your planet. On the plus side, you could put in a space elevator between planets. Two equally sized planets and a smaller moon is a three-body problem, and I remember reading that it is possible but unlikely. Finally, the true limiting factor is [Roche limit](https://en.wikipedia.org/wiki/Roche_limit) (I am too tired to explain). But apparently, [Moon can be a lot closer to Earth](https://en.wikipedia.org/wiki/Roche_limit#Selected_examples) than it currently is. ]
[Question] [ I have been designing a whole solar system for my story, and I am finally able to come down to creatures on the planets. I have already asked a question about one of the planets, Veynerth, so there is more information and updated changes to the planet there. It is a deserty planet for the most part, but there's regions where there's high volcanic activity, and it actually gets very cold due to the ashes and such clouding up the atmosphere and blocking out the sun. Anyway, I wanted to create a creature that lives in the desert parts, and what I have so far is that it's a giant lizard-like creature that burrows into the sand and essentially "swims" in it, finding its prey based on the vibrations on the surface. I don't know how well that would work because I think that it having a rough, scaly body would make it hard to swim in the sand. I wanted to know if there was anything I could change about the design to make it more plausible, yet still retain that lizard-like appearance. Extra details: They have secondary clear eyelids to protect their eyes from the sand. They don't need a whole lot of water to exist so they can spend weeks underneath the sand waiting for prey. They have trouble walking on land because they evolved to dig/swim through the sand. This makes them very slow and not so menacing if you could ever isolate one on solid ground. Please let me know if you need me to add more details. Apologies for my lack of artistic ability, but here's what I have sketches for what it would look like. (<https://i.stack.imgur.com/sPNzN.jpg>) [Answer] I think the creature you're designing already exists. It's a lizard called the [sandfish](https://en.wikipedia.org/wiki/Scincus_scincus): ![Image of sandfish](https://i.stack.imgur.com/twJTPm.jpg) Image source: [Wikipedia](https://en.wikipedia.org/wiki/Scincus_scincus#/media/File:Apothekerskink01.jpg) This creature spends most of its time under sand and has developed a special respiratory system to keep sand out of its lungs: > > [Scientists] found the lizards breathe out with about 60% more intensity inside their sandy burrows than when they are aboveground, which might allow them to expel sand particles from their nostrils. The scientists also estimated a 70% drop in the speed of inhaled air when it hits the widest section of the lizard’s respiratory tract. This likely means that as the air slows down, sand particles fall and get trapped in mucus and cilia that line the section, the scientists report today in the Journal of Experimental Biology. From there, some particles are blown out during exhalation and others are swallowed, after which they pass through the digestive tract and out of the body. > > [How the sandfish lizard stays sand-free](http://www.sciencemag.org/news/2016/11/how-sandfish-lizard-stays-sand-free) > > > [This video](https://www.youtube.com/watch?v=P4bxRj-BjFg) shows what motions it makes to propel itself through the sand. [Answer] Their body would require tremendous force to move through sand relatively quickly and it should be able to withstand the pressure of all that mass of sand above them. Other than that, I do not doubt on the ability of their scales to resist sand "grind" while moving. By the way, some reptiles already have [a second eyelid](https://en.wikipedia.org/wiki/Nictitating_membrane). I think they would move more easily if they dug with their frontal claws rather than "swimming". [Answer] I'm visualising a sort of torsioning reptile, that would move quickly through the sand in a fast spinning motion, like a screw. It would need tough scales and a fairly streamlined body for that. That or you could refer to the answers above and have it dig through the sand rather than really 'swim'. ]
[Question] [ Assuming we have the tools and materials of the late medieval period in Europe (~ 15th century) but are allowed to use modern knowledge of metallurgy, what method/process of steel production would allow the highest quality steel to be produced if the measure of quality was its use in medieval weapons and armour? It doesn't have to produce industrial quantities of steel, but there should be enough of it to feed a few smithies. Any source of iron available in medieval Europe can be used, so both mined iron ore and bog iron are available, as are any others I may not know of. Does this change if we add some kind of magic fire to the mix that can achieve temperatures in excess of 2000°C and if so, what process is now the optimal choice? EDIT: To clarify: I'm not asking about the methods that were actually used and available in the 15th century. I can easily look those up. I am asking which superior methods could still be implemented with 15th century tools and materials assuming the neccessary knowledge of said methods. [Answer] Well, the answer is as others have already repeatedly said [crucible steel](https://en.wikipedia.org/wiki/Crucible_steel). However what I have not seen others mention is the correct type of crucible steel for your question so I'll answer anyway. The highest quality method of producing crucible steel was developed by Benjamin Huntsman. It produces the "Sheffield steel" you might have heard of although the term isn't really in use anymore. Historically this happened in the 18th century but none of the technical requirements is really beyond your timeframe. Actually a cursory Wikipedia browse suggest that your desired period just happens to be earliest when this might have been possible. Both the production of coke and production of blister steel by cementation happened just around that timeframe. The steel produced was actually better than early industrial processes could produce and had more uniform quality than with earlier forms of crucible steel. It was first steel that allowed practical mass production at high quality. However the process was harder to scale than the later industrial processes so the steel produced was significantly more expensive. The details are explained in the linked Wikipedia article about crucible steel which makes it pretty puzzling that this was not mentioned despite crucible steel being mentioned and offered by pretty much everyone. [Answer] The most effective method at that time would have been crucible steel. It's made by melting cast iron along with sand, glass, ashes, or other fluxes, in a large crucible. This technique produced a mix of very high-carbon and very low-carbon steel that, when sanded and polished, would produce the swirly Damascus steel effect that's very popular these days. [Answer] I'd personally go with Damascus steel, especially if there's access to magic to bump up the heat. The main issue with straight-up crucible steel is the inconsistencies created from mixing materials with different melting points together and trying to engender proper homogeneity. If you can make that sucker hot enough, you can smooth out the 'bumps' enough to fold the steel and get something very Damascus-like. [Answer] Crucible steel. Anything past that is overkill for the medieval era. In late medieval period it was already available and with modern knowledge you could improve the quality significantly. ]
[Question] [ Natural uranium (NU) is a mixture of about 0.7% $\ ^{235}U$ (fissile) and 99.3% $\ ^{238}U$ (non-fissile). To create uranium-based nuclear weapons NU has to undergo a process called enrichment in order to increase the ratio of fissile uranium. Today the ratio of fissile uranium in NU is about 0.7%. However, $\ ^{235}U$ decays faster than the non-fissile $\ ^{238}U$: $\ ^{235}U$ has a half-life of [$7.04\cdot10^8$](http://www.nndc.bnl.gov/nudat2/reCenter.jsp?z=92&n=143) years. $\ ^{238}U$ has a half-life of [$4.46\cdot10^9$](http://www.nndc.bnl.gov/nudat2/reCenter.jsp?z=92&n=146) years. and perhaps a few billion years ago natural uranium was already weapons-usable without the need for enrichment. --- Questions: * Is my assumption correct? Would it be possible to have weapons-grade NU in the past? Say 4.5 billion years ago, when our planet was created. * Could nuclear terrorism be a threat to the existence of extraterrestrial civilizations that form on a planet where NU is already weapons-usable without need for enrichment? Note: I'm asking because I'm wondering if it's possible that some extraterrestrial civs have evolved in planets with enriched NU. This question is not about humans; our past is history. [Answer] ## TL;DR Probably yes, natural uranium (NU) is usable in weapons in "young" [note 1] solar systems. (not weapons-grade, but weapons-usable) Probably yes, terrorists would have a much easier time creating (crude) nuclear weapons. Whether not needing enrichment would hinder or help civilizations prosper and survive is uncertain since there are both problems (terrorism, nuclear proliferation) and benefits (cheaper nuclear energy). --- ## NU enrichment levels 2 billion years ago NU was enriched enough to sustain a nuclear chain reaction ([Oklo cave](https://apod.nasa.gov/apod/ap100912.html) was probably a natural nuclear reactor) 4.5 billion years ago natural uranium was already enriched enough (~23%) to be used in weapons without the need for further enrichment (although enrichment would still be beneficial). Using the code at the bottom we get the following results: ``` 2 billion years ago natural uranium was 3.7% enriched. 4 billion years ago, 16.7%. 5 billion years ago (about the age of our solar system) 31%. 6 billion years ago, 51%. ``` On the other hand we are not quite certain how life on earth formed and perhaps there is a time threshold on how fast life can form in a freshly created solar system, eg. requiring at least 1 billion years for multicellular organisms to form etc. By going into an even earlier period higher enrichments are possible but probably unlikely, since $\ ^{235}U$ and $\ ^{238}U$ are created through the [r-process](https://www.physics.ohio-state.edu/%7Entg/6805/slides/rprocess.pdf) and their abundance when created is probably not that different (about [1.5 $\frac{\ ^{235}U}{\ ^{238}U}$](http://large.stanford.edu/courses/2013/ph241/roberts2/) = 60% enrichement in supernovas). By comparison U used in nuclear reactors is about [3-5%](https://www.nrc.gov/materials/fuel-cycle-fac/ur-enrichment.html), meaning that both state-owned nuclear weapons and nuclear reactors are widespread in planets that are "young". So, yes. Natural uranium was weapons-usable and perhaps is weapons-usable in other "young" solar systems as we speak. Is the relative age the only way to have enriched NU? If uranium can be transfered to a planet by asteroids or comets just like [water on Earth](https://www.space.com/27969-earth-water-from-asteroids-not-comets.html), then "young" age is not the only way to have planets with enriched NU. ## Nuclear terrorism When it comes to terrorists (today): > > once they have [the nuclear material], [80% or more of the way](https://youtu.be/zVhQOhxb1Mc?t=48m46s) [to a crude nuclear bomb] > > > [Also](https://youtu.be/MnW7DxsJth0?t=24m39s), > > once enriched from 0.7% U-235 to 4.5%, ~3/4 of the work of going to 90% U-235 is done > > > > > having a stock of LEU could allow a country to enrich to HEU more quickly, or with a smaller, easier-to-hide facility > > > Meaning that the greatest obstacle is U enrichment. With that out of the way, everything becomes much easier! Both nuclear proliferation and terrorism would be increased. Perhaps that's an extra [great filter](https://waitbutwhy.com/2014/05/fermi-paradox.html) for civilizations on young solar systems. Once they've solved the terrorism/wars issue naturally enriched U is a blessing instead. Perhaps one day we'll be able to detect nuclear detonations from distant solar systems and we'll find out. Note 1: "young" compared to when the nearby supernova exploded creating its elements (including the U). Note 2: I answered my own question so that you can check it. If you find any mistakes, let me know. --- [Answer] # No Weapons grade Uranium-235 is enriched ~90%. Generally, enriched uranium for research is kept below 20% to prevent weapons proliferation. Commercial reactors will use maybe 5% enriched uranium. However, even at 20% enrichment, the [critical mass](https://en.wikipedia.org/wiki/Critical_mass) of U is about 400 kg. From the [World Nuclear Association](http://www.world-nuclear.org/information-library/nuclear-fuel-cycle/conversion-enrichment-and-fabrication/uranium-enrichment.aspx), Uranium must be enriched to at least 90% in specialized facilities to be used for bomb-making. Most of [Little Boy](https://en.wikipedia.org/wiki/Little_Boy#Design) was enriched to 89%, while the average enrichment was 80%. These are the enrichment levels you will need to make a bomb. Finally, [this paper](http://www.princeton.edu/~aglaser/2005aglaser_why20percent.pdf) provides evidence that 50% enriched Uranium is not a significant danger for weapons proliferation. # Conclusion Even with 31% enriched Uranium 5 billion years ago, any terrorist would still need access to an enrichment facility or a breeder reactor (to create Plutonium). In other words, while the work that needs to be done to create a bomb is lower in this 'young' world, the facilities needed do not change, so being a nuclear terrorist is no easier. [Answer] Also consider Plutonium-244 With a half life of 80 million years, you will have to evolve quickly indeed, but it could probably be made into nuclear bomb material without any isotope separation, just chemical separation (I'm unable to get information on its fissile properties). So what could have happened is that in your solar system, there was a supernova 50 million years ago nearby, which sent some massively-Plutonium and Uranium enriched asteroids into your system.. [Answer] A 50% U-235(straight from supernova) can be made into a bomb, [as shown in this answer](https://worldbuilding.stackexchange.com/questions/14060/how-could-a-civilization-with-approx-18th-century-technology-weaponise-mined-nu/87860#87860). But 4by ago it had about 16.7%(number stolen from Fermi\_paradox answer). Critical mass for 20% [is 800 kg](http://nuclearweaponarchive.org/Nwfaq/Nfaq4-1.html#Nfaq4.1.7.1), 245 kg with good Be reflector! So I guess you could make a bomb out of 16.7% U with big reflector, but device would be very heavy and not as reliable. ]
[Question] [ This question already has answers here: [What are the enabling factors for melee combat in modern or future settings?](/questions/3358/what-are-the-enabling-factors-for-melee-combat-in-modern-or-future-settings) (17 answers) Closed 5 years ago. What non-Frank Herbert explanation is there for training solders in the use of slashing or stabbing weapons in an age of hand held laser projectile weapons? [Answer] 1. Technology fails sometimes --- be prepared for when you can't hide behind a random storage case and shoot at your enemy like a coward! 2. Your enemy won't always be content to hide behind random storage containers fifteen yards away from you, trying to plink you with their own lazer guns --- some may be creeping along the service conduits above your position, only to drop down behind you! Others may phase-shift right in front of you! Some's armour or even skin might eat your weak little lazer pellets for lunch as they come charging towards your position! You'll need something sharp and pointy for close in work. 3. Some technology is just too finicky to be playing at Okay Corral --- just like shooting a lead bullet inside an airplane is a dumb idea, so might shooting a lazer gun inside a shuttle craft or on the bridge of a Starmada destroyer. Lots of computer & display terminals, input devices and so forth that took the IT guys ages and ages to cobble together, and you want to punch all that work full of lazer pellets! 4. The sword is simply a more elegant weapon, a weapon of flowing motion and graceful warriors caught up in the Dance of Death, struggling to be the one remaining to bow at the end of the set. [Answer] Same reason we have bayonets and trench knives. Sometimes you run out of ammo, damage your primary weapon or drop it, and sometimes close quarters and speed require them. Also stealth reasons, the classic laser beam points straight back to the shooter and may not be immediately lethal depending where you hit and doesn't cause massive bleeding, but chopping off your opponents head is definitely lethal. Slashes may not kill immediately but they don't cauterise the wound as they hit so massive hemorrhaging is just as lethal. Intimidation, a sword or knife is a very intimidating weapon. If terror is part of your military strategy then a few examples of hacked to pieces bodies would be pretty terrifying. [Answer] 1) It's dangerous to use the kinds of weapons you are talking about because science. For the same reasons you would not use a flame weapon at a gas station. It's not conducive to anyone's survival. 2) Shortages, both regulatory and/or apocalyptic in nature. There might be hand laser weapons, but getting your hands on the power-packs is very difficult. You can jury rig something, but it isn't going to last. Best save it for emergencies. 3) Security Alert!! The second a weapon that's high tech fires, BAM, the feds are there. Security tech locks on your position pretty much instantly, trapping you. with a bladed weapon at least there's a chance. This can be a planetwide automated system controlled by an AI, which nobody can do anything about, so they have to work around it. Or it can be something that's developed for the battlefield, a lock targeting system that makes laser weapons a bad, bad idea. 4) Treaties. Hear me out here. Mutually assured destruction...While there are laser weapons, an agreement is in place. Anyone uses them, they become the bad guys and alliances are formed against them. 5) War is actually thought of as a game, by those higher up. It's a gentleman's agreement to use blades. 6) Lazer guns destroy the value of something that needs captured. Might be tech, might be something else (like nature). Along the lines of delicate tech being around like in elemtilas' answer. [Answer] Because they are better in some situations? Basically you start by giving the laser weapons some major drawback that makes them useless in some situations. And yes, this is the generic form of the Frank Herbert explanation. But it can't be really helped since the military will not waste time training soldiers to use something unless it superior to their other weapons in a some situations. Fortunately we can narrow it down some by noting that people would still have access to the guns we currently have, so apart from some speculative superiority over hypothetical future weapons of unknown properties they also need to outperform weapons we know about and understand. There are some obvious things mostly already mentioned by others. No need for ammunition, can be used silently and without a visible flash, harder to break thru abuse or lack of maintenance, training itself might be beneficial, vastly reduced chance of collateral damage and some defensive ability without damage to opponent. Unfortunately non of these really justify a sword. Any melee weapon can do. In practice a knife is more convenient to carry and if it can be affixed to your laser rifle works as a spear which is superior to a sword in most cases where a knife is not. An axe is also possibility as it is a useful tool in wooded areas. As also already noted by others it is practical to use hardware you are already carrying anyway as a melee weapon. A laser rifle can be robust enough to use as a club. A shovel (or a tripod) can be used as an improvised club or even mace. Training soldiers in such use would generally be more useful than adding another weapon for them to carry. And if your army is aggressive about melee training to increase aggression or physical conditioning they can actually modify their hardware to be more usable. If you train soldiers to use the rifle as a basis for a melee weapon, you will design the rifle to be robust enough to handle that. You will add the hand grips to make the rifle easy to swing as a mace. Attachment to affix a blade so you get a short spear is cheap and obvious. But a weapon might have striking surface for swung use as well. Bit of hardening would make a good mace. Affix a cutting blade and you have an axe. Albeit not a particularly good one. Typically, Ithink the main point of going that far would be to condition to soldiers to keep fighting even when they cannot use their rifle. [Answer] Ace Levy: Sir, I don't understand. What good's a knife in a nuke fight? All you have to do is press a button, sir. Career Sergeant Zim: Put your hand on that wall, trooper. PUT YOUR HAND ON THAT WALL! Career Sergeant Zim: The enemy cannot press a button if you have disabled his hand. Medic! starship troopers. <https://www.youtube.com/watch?v=B203twyaMfM> ]
[Question] [ The main creature in question is an intelligent species that stands from 3' to 4' tall on average. They are heavy-set and primarily bipedal, but able to move comfortably on all fours at the same speed as when upright. Don't think muscular like a typical fantasy dwarf, think a cylindrical torso with short limbs and a large head like a mole. Though they do use technology in wood-boring now, I want them to have a natural method they evolved with, and that is the subject of the question. Possible methods of natural wood-boring I have considered include: * Using claws like how a mole digs in dirt, * A chisel-like structure in their head like a woodpecker, * Chewing like a wood-boring insect, * And chemically removing the wood with some naturally produced enzyme. Which of those methods, or combination of those methods, would be most efficient at creating tunnels in wood within which this species can move freely? I'm also open to suggestions of methods of wood-boring that I didn't mention. It's worth note that while this species is my primary concern in the issue, the world in question does have a number of other wood-boring species of similar or slightly larger size, but the others aren't sapient. Update: Magical solutions are acceptable, and are probably among the advancements in wood-boring tech this race has made, but for answers to this questions, it must be something like an innate magical or supernatural ability. Anything that has to be taught or studied counts as tech for the purposes of this question. [Answer] Giant Beaver Teeth! [![giant beaver](https://i.stack.imgur.com/K1NU0.jpg)](https://i.stack.imgur.com/K1NU0.jpg) from <https://msu.edu/~yansa/> I like this picture! And I think one could make a good case that nothing goes thru wood with only its own equipment faster than a beaver. This source <http://animals.mom.me/long-beaver-chew-down-tree-11371.html> says a beaver can take down a 5.5 inch tree in minutes. And that is regular beavers, not one of the Pleistocene giants Dr Yansa is posing with here. Those were big beavers, 3 to 4 times bigger than the beavers of today. I here assert the wood chewing powers scale up too. <https://prehistoric-fauna.com/Castoroides-ohioensis> [![beaver comparison chart](https://i.stack.imgur.com/zO8fh.jpg)](https://i.stack.imgur.com/zO8fh.jpg) It is interesting that the giant beaver looks to be just about the size creature you need, and it is standing on its back legs as if auditioning for the part! [Answer] # Use termites If you species is intelligent, then perhaps it is intelligent enough to just use termites to do the job. Stick some termites on the part you want cut, maybe induce them by putting some delicious-to-termites substance on the bits of wood they want chewed, then let the termites do the rest. These creatures could have evolved symbiotically with the termites. A comparison to this method from nature would be [birds that rub themselves](https://www.npr.org/sections/krulwich/2012/10/04/162296009/animals-who-love-to-rub-themselves-with-ants-is-this-addictive) with various compounds from ants. This kills the ants, but it is similar. Another similar in-nature domestication technique would be [ants 'farming' aphids](https://www.sciencedaily.com/releases/2007/10/071009212548.htm). The ants keep the aphids fed, and the ants get back a honeydew the aphids secrete. [Answer] ## Combine localized degradation with physical tunneling Wood can be a quite sturdy material but there is one thing it is very vulnerable to and that is rot. The species you mentionned could have evolved an organ near the saliva glands that produces specialized cells that can be spat on the wood during tunneling, these cells have the following characteristics: * They replicate and act like funghi, producing water, oxygen and a chemical like hydrogen peroxyde (H2O2), to break down cellulose and cause [brown-rot](https://en.wikipedia.org/wiki/Wood-decay_fungus) (possibly massively accelerated by some kind of magical catalyst) that causes wood to become as brittle as sand. * They produce a hormone-like chemical which in the right quantity kills them off immediately. This acts as a biological self-regulatory mechanism which limits the rot to a certain area by killing the cells when they become too numerous. The animal produces these while tunneling (which makes it very very fast and easy as the rotten wood part gives way almost instantaneously). The tunneling itself is done by using bone-like structures (around the head for example) and rotating very fast (which could be more efficient for digging than bucal pieces). Icing on the proverbial cake: The wood can rot into pretty good fertilizer. For more info see [video I found on wood decay](https://www.youtube.com/watch?v=zdwdMQxNiNs) [Answer] Chemical Boring. I presume the animal eats the wood as it goes. In that case the most energy efficient way to dig the tunnel is to digest the wood and suck it up like a milkshake. The animal smears its stomach juices on the wood and waits for it to soften. Then it slurps up the softened wood up and repeats. Yum Yum. To see what this feels like place a biscuit in your mouth and leave it there. I suggest generic Digestive Biscuit. The biscuit will absorb the saliva from your mouth and fall apart. This is more efficient than what a beaver does, since the beaver spends energy chewing the wood with its teeth, and then digests it. Your not-dwarves save energy on chewing. [Answer] #### Chewing/biting is more efficient than clawing or cutting Woodpecker-style or mole-style are about banging something sharp&hard against the wood to break it. The harder and sharper the tooth/claw, the more progress it will make. Human tools like a knife, axe, and pick all work this way. Chewing is a different mechanical process that involves two opposing blades. Scissors or shears is the analogous human tool. Two opposing blades are more effective than one thumpy blade. ]
[Question] [ First post here so hopefully I'm asking this right. I checked to make sure there wasn't an answer out there already and didn't see anything, Either way... I've got a species that can't communicate with others but does communicate among itself quickly and clearly. So, an imperfect Hive-mind. they are going to be a galactic grade threat and thus they're going to be going against other species that wish to end them in many ways. But I want there to be an actual method to how the hive-mind communicates. However, I can't think of a method that couldn't be spoofed by other species So my question is: what possible methods can they communicate to each other with that couldn't be spoofed by technology as soon as someone realizes how they talk? It doesn't have to be completely foolproof, just not something that could be turned against them within days or weeks. What I mean by Jammed and Spoofed is that the communication is rendered useless, either there's too much garbage being sent to pick out real messages or there's too many fake messages to pick out real ones. Regardless, the end result is they can no longer communicate because of the efforts of another species. The hive-mind has no queen. There is a limit to their natural range, but there's equipment on their ships for communication at much longer distances. This equipment only amplifies, it wouldn't allow anyone to tap into the hive-mind. [Answer] This is a tough one, because any method which depends on natural phenomena will be vulnerable to other species' science. That is to say, if they communicate by radio, someone will pick up their communication when scanning for radio waves. And so on. (Hey, how are they supposed to communicate across interstellar distances anyway?) So we need to get clever. Some thoughts... * Go quantum. Quantum works for everything! ;D Specifically, the Hive Mother back on Planet X implants a particle in each offspring; the H.M. has in her body another particle which is quantum-paired with it. Vibrating the particle in one body creates a matching vibration in the other, hence hard-to-intercept communication. * Similar, but go crypto. H.M. implants public key A and private key B in each spawn. H.M. knows private key A and public key B. Spawn sends messages encrypted with A, and HM can decrypt them with private key A. And vice-versa. Eventually, a detailed biopsy may be able to retrieve the keys and start messing with the messages, but it may be ... difficult. [Answer] This is pretty trippy. Strap in. 5 spatial dimensions. Imagine 1 dimensional creatures. They lives along a line. They move along it left and right: the only two directions possible. From a Flatlander two dimensional perspective outside the line we can see them moving left and right along their line. Flatlanders also move back and forth in their 2 dimensions. From a three dimensional perspective we can look at the line like a Flatlander. But we have up and down and we can rotate to see all the 1 dimensional creatures in the same space, overlapping. By coming up and looking down onto their line the line becomes a point, and all of the 1 dimensional creatures are in the same dimensional space. Now the trip. From a 4 dimensional perspective we can see 3 dimensional creatures like ourselves moving around in our 3 dimensions. But from a 5th dimensional (5th spatial dimension) perspective we can see that all 3 dimensional creatures are in the same 4d space - overlapping each other from this perspective, just as the 1d creatures overlap from a 3d perspective. Your hive mind uses this. They all overlap with each other from a 5th dimensional perspective, and also overlap with everything else in our 3d universe. It is noisy, all crammed in there together with all that there is. But even in a noisy party I can hear you if you come up close and shout into my ear. If you were actually in my head, you would not need to shout. You would think thoughts right into my head and it would be easy to hear. That is how their hive mind works. Their minds are in different 3d spaces but not different 5d spaces. --- 3 spatial dimensions and 1 temporal dimension... and 1 more dimension. The prior considered a 5th dimensional perspective in the context of a 4th spatial dimension. But if the 4th dimension is time, then what is the 5th? From that perspective, everything has happened at the same time. If you can communicate from a 5th dimensional perspective all of our discussions have happened at the same time. I hear everything you have said and everything you will say, now, always. How to use that against them? For all spatial dimensions, the prospect of creating technology to duplicate 5th dimensional awareness is daunting. The prospect of coopting, or tricking, or hypnotizing one of these creatures and using the creature itself as the entry point... somewhat less daunting. If the 4th dimension is time, the prospect of defeating a creature for which all times are now is even more daunting. Hopefully Team Earth is any the top of their game... --- Dluz glared sullenly at his handful of pretzels before shoving them all in his mouth. Once his hands were free he began to wave them about. "5th dimension? Everything in the same place?" Pretzel fragments sprayed freely. "I feel a seizure coming on just trying to think about it. How can the Hive do it?" Peg phlegmatically picked pretzel pieces off his arm and set them in a small pile. "They're big," he offered. "Big brain." Yesno looked over her shoulder, her hair wreathed with smoke from the grandmother board. "It's not how big it is. It's what you do with it." She winked at Peg. "You of all people should know that, Peg." Peg nodded as he was showered by a laugh of wet pretzel fragments. "Yes. Yes I do." [Answer] For the jamming variant you may rely on effects that are theoretically possible, but are out of reach for the opponent race's engineering level. For example, we (as humans) know today how neutrinos can be generated, what energy spectrum they will have in different processes, we can even modulate neutrino beams thus embedding information, but we do not possess efficient techniques for neutrino capturing. If your race has developed such techniques, then they have upper hand. Same can be applied to gravitational waves, being quite recent discovery means there aren't many devices that can detect them, let alone use them. [Answer] Here are some options: Pheromones, chemical language, viral/bacterial/prion based communication. Member of your hive mind only communicate by direct contact, or by direct contact with something that another member of the hive mind touched (like psychometry, but with chemicals). While others might recognize how the beings communicate, spoofing the messages would require understanding what is being said and how. If you go for bacterial communication, or something like tardigrades, it might be very difficult to suppress a message, as it spreads across the environment (maybe harmlessly), picked up by carriers and/or is difficult to destroy. Alternatively, they could just send flashes of lights and use Morse code. Your beings are a hive mind, so rather than words and letters, they may use logograms and relational concepts (think of the Star Trek: Next Generation episode Darmak and Jalad at Tanagra). Sharing complete understanding with one another, your hive mind might also always be talking in terms of the big picture, instead of specific details (see the Arrival, I think - recent movie with squid like aliens). These different linguistic frameworks, which presume deep understanding of the hive mind (which the hive mind has) can effectively encrypt communication happening in plain sight. Or, since your being is a galactic hive mind they may use multi modal communication, just like we do. We use written words, spoken words, visual signs, clothing, and performance. Your hive mind may use sounds, chemicals, colors (passively) or lights. [Answer] # Quantum entanglement of unobtanium particles At conception alien embryos receive a number of entangled particles of unobtanium from their parents. The parent either keep other half of the entangled pair themselves or give the paired particles to the embryo's siblings at their respective future or past conception. This allows aliens to instantly communicate with their parents and siblings over any distance. Some of the entangled particles may come from the embryo's grandparents, thus enable communication between grandparents and grandchildren and among cousins. We can reuse this over the generations allowing aliens to communicate with their extended clan instantly over any distance. Probably not all aliens can telepathically communicate directly with each other. But by using a common cousin/distant relative as relay aliens might be able to reach almost every other member of their species. The aliens have a mesh network ingrained in their biology (a mesh network might be more interesting than a star topology that results from a single brood mother). Contrary to normal quatum entanglement --which doesn't behave as I naively assumed-- an unobtanium particle can be forced into a quantum state and the paired particle immediatly changes into the corresponding state. The OP can decide whether a particle can be forced into a state once and then untangle or can be use many times. When particle can be set a limited number of times, communication is limited allowing more communication between closer relatives. If you allow reusing unobtanium particles, communication is not limited. It would still allow for richer communication between closer relatives, since the share more particles. As world builder you have a choice: The aliens might 'know' intuitively which particles to affect to communicate with whom. Just like we 'know' which neurons to fire to move our limbs. Or, communication might happen between random relative and propagate at random though the alien society. I imagine that just like in our biology thousands or millions of neurons are involved in thinking of a single concept, thousands or millions of particles are involved in the aliens telepathic communication. It is a messy biological process and not a clean binary one. ## How safe is this from jamming and spoofing? The particles are exchanged via trusted channels. Other races cannot easily introduce fake particles into the alien communication network. Two possible attack vectors to introduce fake particles among the aliens are: * Alien prostitutes that have defected, but this is limited to the prostitute's offspring and takes generations. So it might be impractical. * Capturing aliens; having very detailed knowledge about the communication lobes in their brains; adding fake particles that are entangled with particles controlled by the adversary; releasing the alien without the alien knowing its telepathic capacity has been tampered with. The third attack vector can be used for both spoofing and eavesdropping: * Capture or kill an alien without the alien (auto reflexively) communicating a distress call or destroying all its entangled particles; dissect it again without triggering any defensive reactions from its immune system; take its entangled particles without accidentally untangling them. As long as other aliens believe the dissected alien alive and safe you can access the aliens biological communication network. Do aliens periodically send "I'm alive" ping messages to prevent this attack? Do the adversaries know enough of the alien bionetwork to send these messages at the correct time? This attack might be difficult to execute. These attacks are all limited in scope and practicality. There are probably more kinds of attack. The aliens can have biological or social countermeasures against hacking their quantum bio network. * Do not attack the network channels but attack the endpoint. If you can induce some sort of epileptic seizure into the alien's brain it might jam the unobtanium network and perhaps even cause a cascade. [Answer] It will depend on the scientific principle underpinning the method of communication. In theory this is available to anyone with enough developed science, but as with anything information based it can be cryptographically hidden and rendered reliably secure with enough layers of complexity. If the speed of communication is to be as quick as possible then it will have to be based in particles that approach the speed of light. This is really an information security problem, though. So the answer will lie in codes and code breaking. By jamming a signal I assume you mean stopping the dissemination of information. One would have to have a system where signal interactions with masses/forces would not be possible to avoid jamming. You'd have to imagine a method of high energy particle detection that exploits information only you have. I do not know if such a thing exists. [Answer] It isn't just communication, it's a complete language. Complete with idioms, accents, intonations, cadences, sayings, metaphors and the like. Even if someone could detect the means of communication, understanding it would be very difficult, and reproducing it properly even more so. Aliens, after being addressed by humans/other species, speaking to one-another in a very different dialect to the one used by said humans/other species: "Who's that talking? I understand them, sort of, but they sound all wrong. I've never heard an accent like that, the intonation is all wrong, it's too regular in speed, and why the juvblix would they say all that when they could just have said 'ghallsox vvvved'? Even a new talkling knows that." "Oh, it's those sudggedv aliens trying to confuse us. Just listen to what they say, make the appropriate responses, and remember that they're trying to get us to do the wrong thing, which will backfire on them if we show them what they expect to see, but consider how they might take advantage of our doing what they say." Jamming is by its nature limited in range - even human speech can be jammed, but humans can move away from the jamming. Spoofing a previously unknown language can take years to achieve even for humans with a human language, if it can ever be done at all. [Answer] You prevent others from intercepting, faking and jamming your communications by not having anything anyone else recognises as communication. There are no individuals in a Hive Mind, and it's rare that a single entity of the whole does anything on it's own. Each and every individual knows the location of all the others at any given moment, this info can be passed by radio waves or some other 'normal' communication method. Actual messages are communicated by the locations of individual entities relative to each other. So basically a group of these aliens would change formations, perhaps appear to be dancing, and this would be immediately understood by the Hive. It's hard to spoof because if the motions are subtle enough it won't even be obvious what it is and the radio waves passing between them will be the first thing to be analysed as a possible form of communication. Even if they do decipher the 'language' humans (or other aliens) can't just replicate the radio signals because the Hive would notice if a new entity just appeared somewhere with no prior connection. The only possible way to successfully fake communications would be to start broadcasting a signal while simultaneously killing one of the aliens (replacing it as such). This would need to be done to a whole group to be successful, which would be exceedingly difficult. As for intercepting communications, you'd have to have the full picture of the entirety of the Hive to know what any specific movement means, which again would be very difficult to collect all the signals and process them in any meaningful way. ]
[Question] [ I had this one idea of having the government create chips that monitor the thoughts of prison inmates as a way of preventing future crimes. At the same time still, give them a degree of freedom and mental support. Here was the problem I got into, however. Would a technology that monitors the thoughts of the mind wirelessly really be possible in a hard-science setting? [Answer] While it would make a cool story, monitoring thoughts is not possible in any foreseeable future. First of all, [we do not know](https://www.psychologytoday.com/blog/consciousness-and-the-brain/201202/what-is-thought) exactly how the thought process works and where it is located in a brain. So far [brain mapping produced mixed results](https://www.ncbi.nlm.nih.gov/books/NBK50989/): We figured out that different regions are 'responsible' for different processes, but we still do not understand the mechanics behind it. The complexity of the brain ([human brain has about 85 billion neurons](https://www.frontiersin.org/articles/10.3389/neuro.09.031.2009/full#B24)) and its interconnectedness (each neuron can and does make multiple connections with other neurons) make it impossible to track individual 'firings' of neurons with current technologies. Scientists also stress the importance of neural networks and that the brain is more than a sum of its parts. The second challenge relates to the fact that our thoughts are not necessarily verbalised. [Non-verbal thinking might actually be a dominant form](https://books.google.com/books?id=T9vqGN4V_7AC&pg=PA6&lpg=PA6&dq=non+verbal+thought&source=bl&ots=Toa6wUKnzD&sig=s7YnwgnRgUB4Rax5UVAR0mOFMUI&hl=en&sa=X&redir_esc=y#v=onepage&q=non%20verbal%20thought&f=false). In this case, thoughts exist in a form of pictures, smells, feelings, etc. I am not sure it will ever be possible to transmit these non-verbal thoughts to other people or some devices. It is also important to note that far from all our thoughts are conscious. Moreover, unconscious thoughts are [highly important for decision making](http://www.apa.org/science/about/psa/2009/10/sci-brief.aspx). With current level of technology, we cannot monitor unconscious processes. Maybe in the future with better brain maps we will be able to. However, there is a possibility that background brain activity (like processing sensory input) creates too much noise to identify unconscious thinking, especially if it happens in a non-verbal or similar to non-verbal forms. [Answer] This may be slightly more psuedo-science than hard science, but I just thought I'd give it a shot. I think it could be possible for a sufficiently advanced technology to guess a person's thoughts with reasonable reliability and accuracy, but this is not the same as "reading" thoughts. How would this work? As mentioned in earlier answers, it is possible today to monitor brain activity. While this activity does not in any way describe an actual thought, we do know roughly which area of the brain corresponds with which kind of thought. The trick here is that the technology can, and should, draw data from a whole lot of sources, and more importantly, maintain a comprehensive archive for each human being under its "supervision". For instance, the machine would know when the subject has its amygdala lighting up, and also know the subject is looking at a photograph of his late wife. The machine would detect that the subject was rapidly tapping his right foot, and also picking at his left index fingernail. The machine knows that the man is sitting on his couch, in his home of the last 15 years. There can be many other things a machine could record, perhaps heart rate, breathing pattern, time and date - go wild. Referring to its database of previously recorded actions, the machine makes an educated guess with 78.3% confidence that the subject is recalling his wife, probably a fond memory (if subject is smiling) of a time spent on said couch. The more data is made available, and the more established the database, the higher the probability will be, until it approaches 1. By the way, this is pretty much how most people subconsciously learn to "read" other people close to them, I imagine. [Answer] In a hard science setting I would say no. Currently we are able to monitor many aspects of brain activity via implanted electrodes, nuclear magnetic resonance imagining or other scanning techniques, but whilst these might give some indication that a person was feeling revulsion or joy they are a long way from monitoring thoughts in the same way that a telephone tap monitors a conversation. Due to the complex nature of the workings of the brain it would seem reasonable to assume that this state of affairs will continue, although a break through can’t be ruled out entirely. But even if there was a break through and imaging techniques could read minds in a scanner trying to do this remotely would present enormous difficulties due to the inverse square relationship between electromagnetic signal strength and distance. Making an impossibly difficult situation even worse would be the presence of other people, low level electromagnetic noise from electrically powered devices in the vicinity, power cables and worst of all a potentially moving target amidst other moving objects. In summary if you strap someone into a scanner then almost certainly not, though it can’t be ruled out entirely. But trying to scan someone remotely is just not going to happen. [Answer] Maybe. Sort of. Here's what I mean... There's been some incredible work trying to scan someone's brain and reconstruct the image that the subject was thinking about. Here's an article: <https://www.sciencealert.com/scientists-have-invented-a-mind-reading-machine-that-can-visualise-your-thoughts-kind-of> Here are the results from the machine; first row is original faces, columns underneath are different tries by the machine: [![faces](https://i.stack.imgur.com/PHwc9.jpg)](https://i.stack.imgur.com/PHwc9.jpg) Not awesome, but on the right track, yes? So that's the upside. Clearly different people's visual centers encode info in similar ways, enough to make the machine work. But ... can we assume that the same thing is true for conscious thoughts? That is, will two people have similar brain patterns while thinking similar thoughts? If it's even true, is this pattern language-independent? Chomsky, Sapir, and Whorf are slavering to know. I am a ... little dubious about this. I am not aware of any research along these lines, so I can't cite it. TL;DR -- Imagery, probably. Higher thought, I have doubts [Answer] We can currently monitor brain activity (but not thoughts) using a variety of scanning technologies and these are very important research tools. An example would be the use of [functional MRI scans to study the operation of psychopaths' brains](https://www.webmd.com/brain/news/20130925/brain-scans-show-why-psychopaths-dont-feel-your-pain) and how they might be functionally different from "normal" brains (whatever normal is anyway :-)). Now it's a stretch from that to actually monitoring thoughts, but it's certainly a possibility - i.e. I couldn't rule it out as impossible. We are currently nowhere near able to convert brain activity from such experiments to thoughts - I don't even know of a practical definition for what a thought is, let alone a way to "measure" one, as it were. But we can monitor our own thoughts : we do listen (or in the case of deaf people, typically see sign language) for our own inner thoughts. Presumably there must be some functionality in the brain that does this. It must be reasonably consistently implemented from person to person, i.e. use the same underlying mechanism. The problem is that it quite possibly involves the entire brain, so in a sense you have to model quite a large part of the brain to relate one person to a "standard". But it might be possible in the future. I think more practically we would not bother monitoring thoughts, but simply emotional and physical state. That, combined with simply monitoring location and movement patterns as well as IT activity, possibly eye tracking behavior (e.g. always looking at small children while your brain is in "sexually aroused" mode, or have a pattern of violence-related brain activity while e.g. talking to your girlfriend) might all be used to indicate potential problems and intervene before they become real ones. You might also want to reference [Michael Crichton's "The Terminal Man"](https://en.wikipedia.org/wiki/The_Terminal_Man) for how similar technology could be used to try and prevent thoughts becoming actions. Regarding the possibilities of using this in prisons, possibly with a therapeutic aspect. Prisons are (more or less) controlled environments. It's a lot easier to impose a regime of regular (or irregular) monitoring on someone in a prison than outside. It's certainly realistic to imagine inmates someday being scanned while stimulated by e.g. video, audio, perhaps smells, sensation, to see both how they react (and hence predict possible triggers, issues) and also, longer term, to help work out how effective therapies are working (and ideally use the monitoring to guide the therapy choices). Scanning systems at the moment are non-invasive. There's no advantage to implanting something if you don't need to. If you get enough from just sitting the inmate in an MRI for a hour to figure out how things are going, then it's fine. I think that's possible (not just plausible, but just not possible yet). One major issue : what if your monitoring says someone is not responding to treatment ? Do they still get released when their sentence is over ? Should they be kept in prison ? I suspect an effective use of such a system would entail a radical alteration of how we deal with criminals legally - probably an entirely redefined way of looking at the purpose of prison and the subject of constitutional rights. ]
[Question] [ So I decided to revive an old project which I was seeking assistance a year ago on the realism of the worldbuilding. WB links from the past: [Reality of a tidally locked planet](https://worldbuilding.stackexchange.com/questions/41014/reality-of-a-tidally-locked-planet) and [Slowly Sculpting the Planet - Sky within a Red Dwarf System](https://worldbuilding.stackexchange.com/questions/42205/slowly-sculpting-the-planet-sky-within-a-red-dwarf-system-contd) In short, my world is a planet orbiting around a red dwarf. Since it is generally habitable (I will make it habitable if it isn't, and it's not decided yet the habitants are descendants of earthlings or just humanoid that evolved on this planet) both the day an night side of the planet are developed and populated. However, due to political influence/cultural difference/technological constraints, "day" hemisphere and "night" hemisphere became two big "nations" being diplomatically hostile or at least opposite to each other. After generations, habitants from either side of the planet have never seen people from the other side. For an important plot purpose I would like to have a celestial object that is only detectable from the night side of the planet but hidden/invisible to most of the day hemisphere. At first I was thinking of this: [![Red Dwarf System 1](https://i.stack.imgur.com/zAxCr.jpg)](https://i.stack.imgur.com/zAxCr.jpg) Basically the planet is having a natural satellite with a geostationary behaviour, thus it's hidden from most of the day hemisphere. However after a bit of research, I figured out that a tidally locked planet is unlikely having a natural satellite. Even if it exists the system will be unstable. Then I came of this: [![Red Dwarf System 2](https://i.stack.imgur.com/pd8PC.jpg)](https://i.stack.imgur.com/pd8PC.jpg) Two planets are synchronized in orbital period, they have the same length of a year and the smaller planet will always be in the shadow. Will it be too much of a coincidence or is it scientifically possible? If both are not possible, is there a third proposal that can be compromised? I don't mind artificial satellites, but the problem is that it's not large enough for the part of the story to take place. I would want enough room for this celestial object to have equipment and underground systems implemented which is completely unknown from the day side. Any out of the box suggestions will also be appreciated. Thank you! [Answer] > > The good, the bad, and the ugly > > > The Ugly All it takes to prove the existence of a planet, even one that is visibily hidden, are observation, time, and mathematics. We've been proving the existence of "bodies of mass" for a long time because orbits don't make sense unless everything is taken into account. Therefore, while your planet may be visibily hidden, it cannot be mathematically hidden. If your light side peoples have calculus, they can prove the existence of the planet. Which might not be that ugly, as it could be an interesting plot point. Things you can't see are easily forgotten/ignored, even when a small group of scientists keep reminding people, "there's gotta be something there, and here's how massive it is...." The limitation is that the mass of the two objects will need to be nearly identical (I think) to minimize instabilities. The greater the difference, either the greater the distance between the two worlds (making travel very difficult) or the greater the possibility one will want to orbit the other rather than both orbiting the star. The Bad while your proposed orbit is theoretically possible, the reality is that it is unstable. Any change in mass, distance from the star, even the rotation of either or the worlds (or a passing comet, for that matter), and the orbital sync would fall apart. If either planet has a moon, it's probably impossible (but only an astrophysicist could confirm that statement). However, that might not be a show stopper becasue things can take a honking long time to change when it comes to stellar phenomena, so it might be that the two orbits are not actually sync'd, that one is only just faster than the other, and we happen to be in a... say... 1,000 year period when your hidden planet is actually hidden. That might actually be a useful plot point for you as the existence of the planet would be common enough knowledge for people to not actually think about it (how often do you think about the back of your knees?) and, better still, it's existence would have basically become myth. Of course, those pesky scientists are still reminding people it's there, but your average response might be, "yeah, and according to popular fairy tales, dragons live there... don't we have something more important to talk about?" The Good (or, at least, the really cool) It might be a bit more complicated, but with a bit of handwavium, you could set up an argument for a [Lissajous orbit](https://en.wikipedia.org/wiki/Lissajous_orbit) around [Lagrange Point L2](https://en.wikipedia.org/wiki/Lagrangian_point). Lagrange points are (simplistically) gravitational eddies that can be orbited like an actual body of mass. L2 is directly in line "behind" a planet such that the planet always shields the point from the sun. A Lissajous orbit is one that requires no artificial propulsion to maintain. Granted, it ususally requires a loop around earth to maintain momentum, but I mentioned handwavium, right? This concept could allow you to create a moon that is never seen by the light side. Note that those pesky scientists are still yammering about some mass that keeps affecting the tides (and it would be a wild and wooly affectation, too... did I mention plot point?), but there are ways to discredit/silence/ignore scientists. > > No matter what solution you come up with, it will always be mathematically visible. Tides for moons. Orbital perturbations for planets. Observation, time, and mathematics will detect them all. For the sake of realism, you'll need to deal with this nasty problem in your story. But it's a cool problem, wouldn't you say? > > > [Answer] A synchronized orbit like you described is, simply put, not possible. For every orbit, there is a set speed for that orbit. No faster and no slower. Gaining or losing speed changes the orbital properties. So, something in a further orbit would have a different orbital period. Additionally, eccentricity would come into play, as orbits aren't circular. Things would get out of whack pretty quickly. I don't think it's possible to have a natural satellite in the manner you want. That said, an artificial satellite could work. If the inhabitants are descendants of colonists, the colonists could have established a station in orbit. Using the L2 Lagrangian point and some stationkeeping, it would stay precisely where you want it to. There are numerous reasons for staying in this position, but one significant one is that it blocks out the sun's light, allowing for better celestial observation. What the station was originally intended to observer, or why it is observing, is a different matter entirely. The problem is, in such a position a station or other object wouldn't be easily visible. It wouldn't be reflecting sunlight for obvious reasons, so the only way to "See" it would be to see it blocking stars or other objects. [Answer] Your first scenario could exist for a while, but it is unstable and extremely unlikely to occur by chance. Your second scenario flat-out impossible. I can think of a few more options, but they may not be any better than the first two. In your first scenario, you've got the satellite perched at the planet's [L2 Lagrange point.](https://en.wikipedia.org/wiki/Lagrangian_point) This is one of five points in a two-body system where the gravitational and centrifugal forces on a third body all cancel out and it can sit in place relative to the planet and star. The L2 point, unfortunately, is unstable. The potential there is sort of like a saddle. If the satellite gets nudged ahead or behind the planet (or out of the plane of the solar system), the combined gravity of the star and planet will pull it back. However, the slightest nudge toward or away from the planet will send it out of equilibrium and, most likely, flying out into its own orbit around the star. Such a natural satellite would not remain in place for long. Manmade satellites can exist at the Earth-Moon and Earth-Sun L2 points for quite a while, but that's because they were given a precisely-calculated push and have thrusters to keep them from drifting away. It is worth noting that the L4 and L5 points, however, are stable. A nudge in any direction to an object at either of those points will simply put it in orbit around that Lagrange point. However, as these points are about 60° ahead of and behind the planet in its orbit, you won't be able to hide a satellite from both the light and dark hemispheres there. Your second scenario, as I mentioned earlier, is flat-out impossible. The formula for the orbital period of a planet orbiting a star is given [here.](https://en.wikipedia.org/wiki/Orbital_period#Small_body_orbiting_a_central_body) Note that the only factors are the radius of the orbit, the mass of the star, and a few constants. Planets farther away from their stars orbit more slowly, period, end of story. Your "satellite" will be about as visible from the larger planet as Jupiter and Mars are from Earth. This, however, raises the possibility of a third option: If there is a thick asteroid belt or Saturn-like ring between two planets, that'll increase the effective mass of the star for the second planet, causing it to orbit faster. For this to work, however, the mass of the material in the ring must be an appreciable fraction of the mass of the star. There are a lot of reasons to suspect that this shouldn't work, and frankly, I'm not well-versed enough in the mechanics of this sort of thing to offer a clear opinion. On the one hand, all the material seems like it ought to have coalesced into a planet at some point. On the other hand, [Fomalhaut](https://en.wikipedia.org/wiki/Fomalhaut#Debris_disks_and_planet) has a ring substantial enough to be visible from telescopes on Earth... but then again, the Fomalhaut system is quite young and Fomalhaut itself is almost twice as massive as our Sun. If I were to take a wild guess, I'd say that this scenario is no more implausible than a planet managing to maintain a satellite at its L2 point for long enough for intelligent life to evolve... if the second planet is even visible through the ring at all. [Answer] An interesting configuration that unfortunately still suffers from similar instability issues to those mentioned before is to have the tidally locked world situated at the l1 lagrange point of a large gas giant. Your "hidden object" could then be one of the normal moons of the gas giant. The reason this is an interesting alternative is that the people living on the dark side would not have to live in complete darkness, since there would be light reflected from the gas giant. This might also help stabilize the extreme weather patterns that are assumed to occur of tidally locked worlds due to the temperature gradient. [Answer] One possibility is an object that has an extremely eccentric orbit with a perihelion (closest approach to the star) not too far outside the tidally locked planet's orbit. And a resonant orbital period. Thus the object might complete exactly ten or a hundred or some other number orbits for every one the tidally locked planet does. The outer object with the eccentric orbit would travel faster the closer it was to the star as it got closer to the star. So when it was at perihelion it would be moving very fast as it swung around the star with enough excess speed to travel far back out again. And the duration of it's closest flyby of the star might thus be about the same as the period of the tidally locked planet's year/day. The light of the planet's star scattered around the daytime sky will drown out the light of most celestial bodies except the star. Especially if the atmosphere is more dusty or foggy or opaque on the sunward side of perpetual daytime. On Earth, objects visible in the daytime sky include: 1) the Sun, apparent magnitude -26.74 (the higher the magnitude the lower the brightness) 2) the Moon, apparent magnitude -12.90 at full moon, down to -2.5 at new moon. 3) comet Ikeya-Seki (1965) maximum apparent magnitude -10.00. The brightest comet to be visible during the daytime. 4) Iridium satellites. Maximum apparent magnitude of flares -9.5. 5) Supernova seen in 1006. Maximum apparent magnitude -7.5. 6) Crab supernova seen in 1054. Maximum apparent magnitude -6.00. 7) International Space Station. Maximum apparent magnitude -5.90. 8) planet Venus Maximum apparent magnitude -4.90, minimum -3.2. Objects with apparent magnitude less than -4.0 are not visible when sun high in sky. 9) planet Jupiter. Maximum apparent magnitude -2.94, minimum -1.61. 10) planet Mars. Maximum apparent magnitude -2.91, minimum +1.84. Objects with apparent magnitude less than -2.5 are not visible in daytime sky even when the sun is less than 10 degrees above the horizon. 11) planet Mercury. Maximum apparent magnitude -2.45, minimum +5.7. 12) star Sirius. Apparent magnitude -1.47. All other stars and planets are not as bright as Sirius. There are about 9,096 stars visible in dark skies to average human eyes from Sirius at -1.47 down to stars at apparent magnitude +6.5. Note that it is possible to see a few of the brighter stars and planets at twilight. Perhaps the nightsiders rule the twilight zone and keep the daysiders out of it. The tidally locked planet would not have a moon. The author can decide if the daysiders have any artificial satellites bright enough to be seen in the day. Comets bright enough to be seen in the day are rare in our solar system, and supernovas visible in the daytime are much rarer in our region of the galaxy (which is one of the necessary conditions for life on Earth). The author can decide if those conditions are different in his solar system. The author can decide if there will be any stars bright enough and close enough to be seen in the daytime of his planet. The author can decide if there are any planets in the solar system that sometimes get bright enough to be seen in the day. In short the author can ensure that the only celestial object the daysiders ever see in the sky (except for rare and unpredictable events like supernovae and daylight comets) is their sun. The nightsiders will see the stars all the time and count time by the time it takes for a particular star to rise above the horizon, reach it's highest point in the sky, and set below the horizon, and repeat. They will know that the outer celestial body will take a specific number of such periods to return to sight. So the only problem is to make sure that the outer celestial body is not bright enough to be seen in the daylight sky until it passes below the horizon as seen from the dayside. You may need to have someone run some computer simulations to find a set of orbits that makes the outer celestial body only visible when passing by the night side. It is possible that as the outer object passes close to the night side of the planet it suddenly flares up briefly in brightness due to developing a coma like a comet or having a frozen atmosphere that becomes vapor and makes the body much more reflective. [Answer] Aren't we all overthinking things a little bit? Most planets and the stars are known to be mostly visible at night. [Sometimes you can see Jupiter, Mars or Venus in daylight](http://earthsky.org/space/venus-and-jupiter-dance-in-daylight), but they are relatively faint - even Jupiter can only be seen during daylight with binoculars or more powerful equipment. So all you need is a regular planet on a regular orbit. It must be farther or smaller than Mars, enough that it should not be visible under daylight, but feasible enough still, and quite large enough for whatever you need to have on it. In our own solar system, if Earth had a day ength equal to its year, Ceres would be a good candidate. ]
[Question] [ I'm writing a story about mermaids. For this reason, I'm wondering how much you can hurt someone by say, throwing a punch, hitting them with a rock, or even throwing a spear or rock. I'm not sure how to calculate it. I'll need to work out the drag forces that hinder acceleration, as well as quickly reducing the speed of the attacking object. Can someone help me crunch the numbers for throwing a punch underwater, which can be used as an example for my other calculations? [Answer] Melee type combat has relied on a variety of mechanisms of injury over the millennia. We have lots of options because Air does not provide significant resistance to rotational motion. This makes all sorts of things like clubs and maces practical, slashing weapons like swords, Trebuchets and Catapults rely on it too. All of these get pretty well taken off of the table due to the resistance to be found in water. Not so much from the weapon itself, but from the arm or armature. That leaves you with stabby weapons. Things that produce puncture wounds would be best. This is because the cross section of such weapons would not have any appreciable fluid resistance and they are still effective with slower body motions. Because of this, Your Merfolk are going to evolve tactics based around this. The math is not really necessary. Other answers have brought up various projectile weapon options, and they did it better than I could. Elastic band or spring driven would be best. Just keep in mind that what we think of long ranged and underwater long ranged is going to be different. A system that could launch a Javelin a couple hundred meters in air may only have 20 meters effective range in water. That is going to have an impact as well. Firearm kinds of weapons are going to have major issues. Rifle rounds fired into water slow down to harmlessness in a few yards. The same rounds are often used to take Deer at a few hundred yards. Anything you need to go a long way is going to have to have to have some sort of mechanism to continuously propel it forward. Like torpedoes. If you think about it, torpedoes are the only long range weapons that travel underwater to their targets. Explosives as area effect weapons are still viable. Even rednecks know this. Dynamite fishing anyone? Explosives cause pressure waves that can kill. There are a number of mythbusters episodes that show how this works. Shrapnel is less of a problem underwater. You have options, but they are limited. On the other hand, remember that Underwater you have a 3 dimensional field. Most human battlefields are fought on the surface of the planet. There is a limited up or down component. Even a lot of air combat is based around hitting targets on the ground. Fighter dogfights happen because fighters are protecting the ability to drop bombs on the ground. Have fun with the fishes, just don't sleep with them. [Answer] Having anyone to fight underwater with the same strategy as we know it would be foolish. You can have javelins travel quite fast in water, but you need to devise some other way (e.g.: rubber bands) to throw them because using your arm or a bow will encounter too much water resistance before you manage to throw it. Much better would be to use a lance (i.e.: to swim toward your foe with weapon "on rest", so that your body inertia give it power). In general you need to rely on mass and its inertia to harm, not speed. Any projectile should be "harpoon-like", heavy with small cross-section. Any throwing device should not have swinging parts (use elastic cord, spring or compressed air). It is not by chance that spearguns are made that way. [Answer] I mean easier than doing the calculations, you can go underwater and try to throw a punch, and you'll see it doesn't really work. You generally need a weapon to fight underwater, and then a cut basically kills as it is really hard to stop bleeding underwater. ]
[Question] [ My question is: * Can a human be used as a living ant hill or bee hive, e.g. have insects living inside themselves under the premise that they (the human) are completely immobilized? "Living hill or bee hive" means that the insects burrow tunnels construct structures within the human. [Answer] In short: no. Insect hives and/or colonies are architectural miracles of nature. These hives are built with an understanding of architectural principles that humans developed over centuries. E.g. Ant hives use hexagonal coves, as they provide the same surface area that a square would, are inter lockable and require less material. Humans are basically skin sacks packed with meat. Our organs are packed in tightly and are arranged in a way that makes sense for us. Another big thing to consider is material. Wax and dirt can be manipulated. I doubt sticking one piece of meat to another will form a durable structure. There are termites that actively seal off and open entrances when the colony is attacked. This kind of manipulation simply isn't possible. To conclude: It is extremely unlikely that something as advanced as a hive will be constructed into something living, when there are far better options. [Answer] There are wasps which implant their eggs into living animals (mostly other insects) so that the growing worm can feed on fresh flesh. This of course results in the death of the host. So I would say that in principle it is possible. [Answer] Apparently it is allegedly possible for a mobile and active human to have a slight case of termite infestation, though I don't know how possible it may be for the termites to build a hive or nest in such an alien environment. <http://jamanetwork.com/journals/jama/article-abstract/667395>[1](http://jamanetwork.com/journals/jama/article-abstract/667395) ]
[Question] [ I recently came across [this paper](http://www.nifs.ac.jp/report/NIFS-886.pdf) detailing a plan to use 12 superconducting rings around earth to strengthen our magnetic field. I'm planning on using this same idea for my own worldbuilding. An advanced civilization is terraforming an Earth sized planet that has no natural magnetosphere. They use 12 superconducting rings to create an artificial one. The NIFS paper I linked to gives me a lot of good information that I need to use this idea, but one part of the paper, on page 10, in particular confused me. It says: > > The finite magnetic field generated by a 6.4 MA superconducting ring would necessitate a 2.6 km safety zone adjacent to the cable to assure that the public exposure limit of 5 G is not exceeded. > > > I'm no physicist, but from what I've gathered G stands for gravitational constant. If I'm not interpreting that incorrectly, then my question is what is the relationship between powerful magnet fields and gravitational constant, and why is there a public exposure limit of 5 G? Or, more concisely, what effects would a powerful superconducting ring have on a nearby human? [Answer] I'm reasonably sure that the $5\text{ G}$ there refers to $5$ [Gauss](https://en.wikipedia.org/wiki/Gauss_(unit)). The Gauss is a unit of magnetic flux (named, of course, after Carl Friedrich Gauss). The $5\text{ G}$ figure makes sense, too; it lines up with the recommendations in [this Cornell recommended safety guide](https://sp.ehs.cornell.edu/lab-research-safety/radiation/magnetic-safety/Documents/Magnetic_Field_Safety_Program_Cryo_Guide_v4.pdf) for public areas (Section 5.3): > > All public spaces are limited to less or equal to 5 G for static fields and less than or equal to 1 G for 50/60 Hz fields. > > > [UC San Diego](https://blink.ucsd.edu/safety/radiation/magnet/limits.html) and [the IEEE](http://www.who.int/peh-emf/publications/facts/fs322/en/) concur, coming up with similar figures for areas of regular exposure without shielding. Also, let's do the calculations ourselves! The [magnetic field outside a wire](https://www.pa.msu.edu/courses/1997spring/PHY232/lectures/ampereslaw/wire.html) carrying a current $I$ varies with the distance from the wire, $r$:1 $$B=\frac{\mu\_0I}{2\pi r}$$ where $\mu\_0$ is the [vacuum permeability](https://en.wikipedia.org/wiki/Vacuum_permeability). If we substitute in the author's $I=6.4\times10^6\text{ Amps}$ and set $r=2.6\times10^3\text{ m}$, we get $B\simeq0.0005\text{ Tesla}=5\text{ Gauss}$ - as the author claims. High magnetic fields can of course wreak havoc with the heart and potentially other parts of the body, which is why we need to worry about this. --- 1 I should mention that the equation I used is really just an approximation in the case of a circular wire; it only fully holds in the case of an infinitely long straight wire. However, at such small values of $r$, it works well. [Answer] The biggest hazard will be flying metal. You can find many industrial injuries listed online where a hand or finger was caught between metal and a magnet. I'm not going to link to medical photos. Magnets can effect people directly, possibly headaches and seizures, but for a person to be harmed at the cellular level by a magnetic field might be many orders of magnitude beyond what is being discussed here. It's hard for me to say, because the paper doesn't mention the strength or hazards of standing directly next to the magnetic cable. Reports of cellular damage is measured in thousands of Teslas, a Tesla is 10,000 Gauss. G in this case stands for guass. 5 G is a safety standard for static magnetic fields. A safety zone is drawn at the 5 G distance. Beyond that line metal needs to be removed from clothing, tools secured, etc. [Magnetic Field Safety Guide](https://sp.ehs.cornell.edu/lab-research-safety/radiation/magnetic-safety/Documents/Magnetic_Field_Safety_Program_Cryo_Guide_v4.pdf) [![enter image description here](https://i.stack.imgur.com/IpAaN.png)](https://i.stack.imgur.com/IpAaN.png) ]
[Question] [ The [DoomFleet](https://worldbuilding.stackexchange.com/questions/74586/removing-an-atmosphere-from-a-previously-habitable-world) returns! And this time, it's with a more "Conventional" weapon - That is, projectiles with an antimatter core. Ultra-simple explanation is they have a "small" amount of antimatter in them, maybe a few dozen grams, suspended by some "basic" EM field. Of course, being projectiles, when they hit something, the field generator is destroyed and the antimatter does the rest. The question is not about the antimatter rounds. Those exist in a place that can be handwaved easily. What I want to know is whether an Antimatter explosion would have a unique signature, detectable to astronomers elsewhere. And if so, how far away would it be noticeable? Part of my story has something like this being detectable a few hundred light years away, which may require some rather large AM rounds. [Answer] Yes, indeed. The gamma rays relase a specific amount of energy, both for the final annihiliation and the binding energy which has two different levels. Check out [positronium](https://en.wikipedia.org/wiki/Positronium) for the case of electron-positron aniliation. You’ll have similar effects for the protons and neutrons too. With a detailed x-ray spectum, you could even tell which elements/antielements were used. The pulse of x-rays also might provide a [source for anaylzing the surroundings](https://en.wikipedia.org/wiki/X-ray_spectroscopy) too — numerus instruments are based on various interactions between x-rays and matter. --- The case of [Positron-Electron Annihilation](https://en.wikipedia.org/wiki/Electron%E2%80%93positron_annihilation) in the case where the spins are opposed can conserve total spin by producing two gamma rays, and to conserve momentum they must be equal energy and opposite in direction. So this is a clear spike at the rest mass of an electron (less a small binding energy), 511 keV. If the spins are aligned, you need three photons emitted to conserve spin, and they can divide up the momentum in any manner. However, you can figure out a statistical distribution. Annihilation of the protons and neutrons are messy, since they are made up of more elementary particles. This will be 2000 times greater in magnitude per particle, with the protons themselves equal to the number of electrons, plus however many neutrons you have. But, certainly a statistical distribution of energy in the resulting spectrum, with several complex features (bumps and valleys in the graph). No doubt it can be recognised as such. You might ask on [physics](https://physics.stackexchange.com) just what that is exactly; someone may have a graph handy. [Answer] As noted, the electron/positron reaction will have a very distinct gamma ray signature at 511 KEV, which is enough for any observer to immediately identify this as an antimatter reaction. Protons and antiprotons release a violent stew of charged and uncharged particles. Most of these won't be detected directly, since their lifetimes are measured in milliseconds, but they too decay into energetic photons. > > Here are the specifics of the reaction that produces the mesons. Protons consist of two up quarks and one down quark, while antiprotons consist of two anti-ups and an anti-down. Similarly, neutrons consist of two down quarks and an up quark, while antineutrons consist of two anti-downs and an anti-up. The strong nuclear force provides a strong attraction between quarks and antiquarks, so when a proton and antiproton approach to within a distance where this force is operative (less than 1 fm), the quarks tend to pair up with the antiquarks, forming three pions. The energy released in this reaction is substantial, as the rest mass of three pions is much less than the mass of a proton and an antiproton. Energy may also be released by the direct annihilation of a quark with an antiquark. The extra energy can go to the kinetic energy of the released pions, be radiated as gamma rays, or into down or strange quarks. The other flavors of quarks are too massive to be created in this reaction, unless the incident antiproton has kinetic energy far exceeding its rest mass, i.e. is moving close to the speed of light. The newly created quarks and antiquarks pair into mesons, producing additional pions and kaons. Reactions in which proton-antiproton annihilation produces as many as nine mesons have been observed, while production of thirteen mesons is theoretically possible. The generated mesons leave the site of the annihilation at moderate fractions of the speed of light, and decay with whatever lifetime is appropriate for their type of meson.[[5]](https://infogalactic.com/info/Annihilation) > > > This blaze of energy also has a very distinctive "spike". Much like nuclear reactions are @ 1000000 times faster than chemical reactions, matter/antimatter reactions happen orders of magnitude faster than nuclear reactions. Warships, civilian radiation detectors and astronomical instruments tuned to these frequencies will see a very rapid spike of energy, with the distinctive 511KEV signature. If there was a strike on the target, monitoring of the area will reveal the infrared radiation of the spacecraft, asteroid or moon with a hot spot where the warhead struck. (t should be noted that antimatter weapons suffer the same limitation as nuclear weapons in space: there is no atmosphere to convert the radiant energy into shockwaves. The inverse square law suggests that you actually need to detonate the device very close to the target to cause damage. Nuclear weapons can be used as compact energy sources to drive weapons effects, ranging from "shotgun" charges which can drive pellets at up to 100km/sec, nuclear shaped charges which can drive streams of liquid metal at up to .03 c and even devices which can drive spindles of plasma at .10 c. Using an antimatter reaction to drive these sorts of weapons will provide a much more compact and energetic device compared to a nuclear one. ]
[Question] [ Right, you are standing on Earth 100 million years in the future and observing the sky. What would you see during night and how would a day look like when you look up. Weather is not relevant (no clouds), we can say the Earth's atmosphere is very similar to today's. And there is no light pollution. I assume the Sun would be brighter... How much? And would our known constellation change? If so, how much of a change would you predict? And what about the Moon? [Answer] # Sun The sun is expected to increase its [brightness](http://faculty.wcas.northwestern.edu/%7Einfocom/The%20Website/evolution.html) by a factor of about 2.1 over the first 9 billion years of its life. Using extremely rough measurements, that works out to about 1% brightness every 100 million years. The Earth might be a bit hotter, in complex ways that probably depend a lot more on what we did with all that carbon and whether we humans are still around, but visually, the sun will be about the same. # Moon Over the last hundreds of millions of years, the [moon has receded from](https://en.wikipedia.org/wiki/Orbit_of_the_Moon#Tidal_evolution) the Earth at 22 mm per year. Over 100 million years, that works out to 2200 kilometers. Since the Moon's current orbit is 385,000 km, that is a bit less that 1% farther away. If the Earth still has oceans, tides won't be affected much, and the moon will be slightly smaller in the sky. The moon is also causing the day to lengthen by about 12 microseconds per year, which works out to days that are around 20 min longer in 100 million years. # Stars I haven't found any software that will let you look that far into the future at the constellations. However, the sky would be mostly unrecognizable even a few thousand years into the future, so on the timescale of millions of years we can expect the sky to be much different. For example, many of the brightest stars will no longer exist (Betelgeuse, for example, should supernova within the next few hundred thousand years and Rigel within the next few million years). [Answer] Basically identical to [this answer](https://worldbuilding.stackexchange.com/a/13943) using an even larger number. One lap around the galaxy is 250 million years. So 100 million is plenty of time for them to shift relative positions in a substantial way. I think most of the visible stars are close, so travelling (mostly) as a group. So you’ll see a lot of the same stars, just moved in the sky and changed in brightness. Some stars will no longer be visible, and different ones will appear. See [proper motion](https://en.wikipedia.org/wiki/Proper_motion) in wikipedia, which includes links to software: > > There are a number of software products that allow a person to view the proper motion of stars over differing time scales. Free ones include: … > > > Off hand, I think the appearance will be utterly and totally different. See also [this video](https://apod.nasa.gov/apod/ap170417.html) by ESA’s Gaia and DPAC mission teams: > > …the stars themselves will move. Combining positional data of unprecedented accuracy for two-million stars taken over years by ESA's Earth-orbiting Hipparcos (now defunct) and Gaia satellites, a future extrapolation of star movements was made over millions years. As shown in the featured video, many stars make only small angular adjustments, but some stars -- typically those nearby -- will zip across the sky. Once familiar constellations and asterisms will become unrecognizable as the bright stars that formed them move around. Not shown are many local nebulas that will surely dissipate while new ones will likely form in different places. > > > ]
[Question] [ In a [previous question](https://worldbuilding.stackexchange.com/questions/74117/determining-sufficient-nutrition-with-minimal-technology) we determined that to survive on an alien planet, we'd be heavily reliant on stuff we brought with us. Whatever plants we could convince to grow that we happened to have on hand, plus "processed" foods using yeasts. Let's assume: * We have access to Bread Yeast, since the original ship had a half-decent kitchen. * We have access to Beer Yeast, since someone was almost certainly brewing something on board, legal or not. * We have access to a limited number of Earth foods that were preserved and able to be planted. Not an extensive list, but things like tomatoes, potatoes, and the like could likely be grown. [This article](http://www.networx.com/article/growing-a-garden-from-the-grocery-store) sheds some light on what might or might not grow. * We have access to wagons and carts and some form of beast of burden for transporting things. More along the capabilities of an ox than a horse - Not something that would be used for personal transport, but good for moving loads. So, we have ourselves fed, but we can't go out into the wild and pick something, or hunt something, and eat it. While they might not be toxic they're not going to be nutritious or sustaining. It's been a century or two since we've made landfall, and we've regressed back to a "Middle Ages," before firearm, technology level. We still have writing, although literacy has dropped. We never really dropped much below middle ages, as we were able to make do with what we had to get this far. We've grown, and split into factions, and then nations, and as nations do, they war. How do we keep ourselves supplied? One of the primary methods of resupply in such a time period was to forage and hunt, both of which are pretty much out. Sure, you can steal stuff from the enemy, but that will only get you so far - Especially since they know this and can adopt a scorched earth policy. What sort of logistical wrangling would be needed to keep an army in the field under such conditions, and what sort of "Maximum Range" would they have, if any? Are there rations that would be sufficiently nutritious that would also keep for long enough? New addition: Could a network of ships and waterways be sufficient, especially if the civilization were built around such areas? There is historic precidence, especially for farming - A significant factor in this world. As a note: I'm not necessarily looking for how warfare would change (That would be the scope of another question), more for how the logistics of keeping an army at a distance would change [Answer] Annoyingly, you don't. Armies stopped foraging because our technology increased. Canned food was a major breakthrough that allowed us to ship large amounts of food over large distances. Without access to light long term storage you're bound by either a supply chain from city to the front or you need to forage what you can. With the first I mean you need a continous stream between your frontline and the city that produces your rations. Very very vulnerable to disruption. You could probably support a squad with a wagon of supplies. Based on what your beast of burden can carry you can determine the maximum amount of supplies it can carry. Divide that by the amount of men in the squad and you got how many days they can be fed, Extrapolate that with how many miles they can march in a day. Half that for the return trip and you got your range of operations. As Kisili mentioned herding is a way out. Adopt a system similar to the mongol horde. That would limit your speed to the speed of the herd animal. But what sustains these animals? [Answer] Herding comes to mind, many ancient peoples lived this way. The Mongols drove their herds with them on the way to battle and survived on them even when the earth was scorched in front of them. So the beast of burden not only carries gear, but is part of the diet and figured into logistics as such. It breeds and multiplies itself as time goes by and it can carry enough seed to plant conquered areas. A sort of non war example would be Polynesian explorers taking plants that could be cultivated on islands that previously had no food plants. The islanders lived off stores, pigs, dogs and fishing for years sometimes until the crops were enough to take over as a major part of their diets. Breadfruit trees for instances take at least 5 years before they can be harvested. But breadfruit paste fermented and prepared properly can still be eaten 50 years later. Your army would do much the same, but live off it's stores and herds. Ox can pull 900kg all day every day, they eat about 11kg (24 pounds) a day, so if managed properly this should be sufficient for quite a long time to carry their own feed, because their numbers would always be dropping as they are consumed. In groups pulling carts this haulage would be a lot more I would think. Although I just got the 24lbs from the internet, no idea how correct that is, but can always supplement their feed with high protein/low volume stuff. They can feed them on straw to fill stomach, and pellets to give the right protein. This is sometimes done with cattle in real life. If the native flora isn't poisonous the ox-like animal could browse on it to fill stomach, and get it's nutrients from pellets. This would increase the length of time they could exist on food they carry dramatically, perhaps indefinitely with intermittent resupply. If it's a native ox like animal that can live off the local flora, then there is no problem at all supplying your army. They don't need to eat the animal, and one of them can haul 900kg worth of human supplies, more than enough to feed a bunch of men for a long long time. So you just need to work out a good ratio of beasts to men. A human can eat about 2.5kg of food a day. So basically 1 ox could take a years supply of human food for one person without resupply. People preserved food before canning, you can look up the different ways. Polynesians fermented and prepared foods that could be stored for 50 years and more. Salted meat, pickled veggies are other ways. Even smoking, drying and storing packed in oil make things last a long time. An extreme was the Mongols several times ate their prisoners when they didn't have other sources of protein. Such a situation could develop on a World like yours where edible protein is not available outside base environments. [Answer] I'm writing this as extension of comments to one of the answers. So you made planetfall about 100 years ago. You lost infrastructure, and a lot of knowledge, but you still know modern common knowledge, and if life expectancy rose high enough, you still have specialists with pre-fall schooling. Thus, your people know about things like bacteria, virii, atoms, where they come from, nature of light and many others. This makes a lot of things easier. You need food preservation techniques. Take a look at [this](https://en.wikipedia.org/wiki/Food_preservation) wiki page for hints. ## As some examples: You can can your food, just remember to pasteurise it (wiki pretends onlu milk and alcohols are pasteurised, this is not true). Something airtight that can survive high temperature is enough. As a kid, I would assist my mom. She would put whatever it is to be stored into jars, close the lid without twisting tight, put in water and slowly heat the water as to not break the jars. This would both kill the germs, and remove air from inside - hot air expands and escapes, after you pull jars out and twist them tight, under-pressure develops and helps keep them airtight. It also makes it easy to find out if they repressurise - lid will visibly pop showing that jar went bad (either it's not airtight, or it wasn't properly pasteurised - spoilage produces gasses). You can use things that store easily, like flour and dried meat. Some creativity would be necessary to design mobile bread bakery (or maybe not, but I'm just not aware?), but one of the points of yeasts is to enrich the dough - yeasts produce some important vitamins for themselves, after we let them do it we kill (bake) them and take what they produced for ourselves. You can salt the food (not very healthy in long term as salt levels need to be truly huge) if you can find source of salt, there's a good reason why salt used to be very expensive in ancient and medieval times - it used to be very important. You can use controlled spoilage. I'm a big fan of this method, because I love sour cucumbers. Basically, you use bacteria (or fungi) to fight bacteria and fungi. It's a traditional method with many variations present in most cuisines. For example: our cucumbers are made by using horseradish (antibacterial and antifungal properties) and brine to ensure only certain bacteria can thrive in jars with cucumbers. Those bacteria (cumbers are washed, but not sanitised in any way, so those are bacteria commonly living in soil) then spoil cucumbers increasing acidity of solution and making sure pretty much nothing else can survive. Jars are more of a covered than closed. If you want them fast, you just keep them in warm place in kitchen, after week they are ready. Jars for long term storage should be kept in cold to slow down the process. I don't know how long you can store sour cucumbers, I never tried longer than 2 years. Arguably this method doesn't fit your narrative, since it needs specific bacteria (I don't know what bacteria, I just know how to get them into my jars), horseradish and dill (flavouring), which are unlikely to be transported on interplanetary spaceship unless you have full agrotechnics pod with soils, bacteria samples and very large collection of plants. But this method exists, in many variations. None of those methods are high-tech. I can do every in my kitchen on my gas-stove. With practice I could do the same on wood-fueled stove, but it's tricky due to lack of fine control over temperature. There are many ways to preserve food, your group benefits from fact that they know WHY they need to preserve it, against WHAT they need to preserve it, and they have a long list of ways HOW to preserve it. Food preservation is and always was important, I fully expect long list of methods to be compiled within few years of planetfall and passed down to next generations, perhaps mentioning that some methods stop being viable as pre-fall machinery starts failing. List will be effective even centuries after the fall, even if basic knowledge is forgotten, if procedures are outlined properly, and adhered to with reverence. [Answer] 200 years should be more than enough for a large set of people to learn which alien plants are edible and which are to be avoided. It should have been enough also for selecting a variant of the yeast which works better with local plants. Nevertheless you war logistic will be based on "take a territory, raid it for food" (another reason to learn how to eat local foods, unless you want to play the "Excuse me, sir, my mug is dirty" a la Berry Lindon under the British army). If your army is exploring new uncolonized territories, they will have to carry along some supply, but again they shall be able to rely on something harvested locally. If nothing at all on that planet is suitable for human consumption you will not be able to sustain a large amount of people. ]
[Question] [ I think this question could be a good complement to [What royal title can an absolutistic ruler have?](https://worldbuilding.stackexchange.com/questions/50590/what-royal-title-can-an-absolutistic-ruler-have/50592). I have a republic, and I need to refer to its current actual leader somehow. Two obvious choices are President or Prime Minister. If I refer to the leader as a President, I’ll automatically hint we’re talking about a [presidential system](https://en.wikipedia.org/wiki/Presidential_system). On the other hand, if I say Prime Minister, it will be clear this is a [parliamentary system](https://en.wikipedia.org/wiki/Parliamentary_system). The issue is, I wouldn’t like to have to decide about the exact form of this republic yet. So, I need a different, probably more obscure title (this would be fitting since the republic in question doesn’t have a 1:1 resemblance to any real-world country). I was thinking about a Consul. Is it a good choice? What are the other possibilities? [Answer] With an assist from [Wikipedia](https://en.wikipedia.org/wiki/List_of_current_heads_of_state_and_government)... # List of Elected Heads of State President - United States, France, Germany, many others... (alternatively, Federal President in Austria) Chairman of the Presidency - Bosnia. Here there are three heads of state (one Bosnian, one Serbian, one Croatian). They are elected together to 4 year terms, and the one with the most votes becomes chairman. However, the chair rotates every 8 months, so everyone gets to ride. Yang di-Pertuan Agong - Malaysia. Means literally 'He Who Was Made Lord,' and is the elected monarch of Malaysia. Nine of the 13 Malaysian states have hereditary local rulers. From among them, a Yang di-Pertuan Agong is elected every 5 years. I suppose you could use any other name for a King or Queen here as well. After all, they elected their monarchs on Naboo. Supreme Leader - North Korea. The previous Kims were technically elected. However, Kim Jong-un has not yet been elected; there was supposed to be an election last year. I don't think anyone was surprised when it didn't happen. Sovereign - Vatican City. The pope is elected, and in his capacity as the head of state (and absolute dictator, really) of the Vatican, his title is Sovereign. Captain Regent - San Marino. Two are elected twice a year. Also serve as heads of government. Note: Pretty much everyone has a President these days # List of Elected Heads of Government Prime Minister - UK, Russia, Canada, Japan, many others. This is the most common name. President - United States, Brazil, Mexico, Indonesia, others. In many countries there is no distinction between head of state and head of government. Chief Executive Officer - Afghanistan. Also valid when mega-corporations become sovereign in a dystopian future. Chancellor - Germany, and Federal Chancellor in Austria. Chairman of the Council of Ministers - Bosnia. Premier - Taiwan, China (if it counts), Niue. The Taiwanese head of government is also called the President of the Executive Yuan. Yuan means court, best I can tell. Head of Government - Morocco, Tunisia. Booooring. Federal Councilor - Switzerland. The Swiss have a seven member group with a President and Vice-President that acts as a collective Head of State and Head of Government. Since the senior member is the President, I didn't mention this in the Heads of State Section. There is also a Federal Chancellor who is a sort of Chief of Staff of the the federal bureacracy. Wikipedia insists that the Federal Chancellor is not a 'member of the government,' but I know duck when it quacks. Captain Regent - San Marino. Taoiseach - Irish. The Irish gotta be different. # Ambiguous titles from the Ancient World Consul - Ancient Rome. Two were elected for one year terms. This is a little more confusing, since there were two consuls and multiple Praetors who all had imperium, the right to command armies, which is normally a thing associated with only a Head of State nowadays. To make it even more confusing, another official, the Censor was held in higher dignitity than the Consuls, yet had no imperium. I would say that if an Ancient Roman republican government were operating today, the Censor would be the head of state an the Consuls would be heads of government. The real power of the Consulship was that it was a pathway to the Senate, which was the dominant power in the legislature-first Roman republic. Dictator - Ancient Rome. Ironically, the dictator was originally elected to a limited term to deal with a military emergency. Tyrant - Ancient Greece. Also ironic, the Tyrants were usually (though not always) elected. I mean, Hitler was elected too, so I guess its not that ironic. Archon - Ancient Greece. This is another confusing title, as there were usually multiple Archons in a given city-state. The Archon Eponymous was the chief Magistrate in Athens, while the Polemarch (senior to him) was the head of the army and the Archon Basileus was the most senior Archon, and something like a head of state. As with Rome, the real power of the Archons in Athens was admittance for life into the Areopagus, a Senatorial body which held most of the power from ~680-580 BC. There were too many variations of government both over time and between city state to mention here... Ephors - Sparta. ...except for the Athenian's ancient rivals! How can we not mention them. Sparta had two kings, but also had five ephors. Again, its hard to tell exactly who was head of state and who was head of government. According the Plato, the ephors had the real power, while the Kings were glorified generals. I'm sure it shifted through time. [Answer] Your title can be pretty much anything you want, but keep in mind that those kinds of titles are as much marketing as anything else. Fearless Leader invokes a banana republic nutjob, President for a career politician. Likewise with Prime Minister. We hear these titles and even though the political reality is different in each case, when we hear the title we get a mental image. With that in mind, and given your worlds political structure, the possible titles should winnow themselves down. Your leader may simply call himself the Tyrant. a simple, clean title that does evoke something sinister, but the evil is a little diffuse. [Answer] Titles are cultural dependent and reflect a given society's history. For example, Supreme Leader might indicate a history where dictatorships or absolute rulers had been the norm. While First Among Equals is the result of a democratic tradition. One suggestion that appeals is First Citizen because it sounds democratic, however, it does have an ancestry that suggests more absolutist power. > > Princeps civitatis ("First Citizen") was an official title of a Roman Emperor as the title determining the leader in Ancient Rome at the beginning of the Roman Empire. It created the principate Roman imperial system. > > > Source:[Princeps](https://en.wikipedia.org/wiki/Princeps) On the positive side this does have the interesting ambiguity of seeming to be equalitarian and democratic yet conceals the iron hand of imperial power. Answers to your question have thrown up a veritable wealth of possible titles. The other answerers are to be commended for their diligent research. [Answer] I just ran two words for ruler together, for example: Regent-General Lord President High Commodore Supreme Governor Chancellor Captain P.S. Feel free to use any of these, hope this is helpful. ]
[Question] [ For instance the size of an industrial garage door on a space station? Assume 1atm inside and 0 outside, anything is on the table from gaskets to some kind of embedded heating system around the seams capable of welding and unwelding the door as long as technically possible to build. Must use actual materials and engineering practices. Sliding doors might also be acceptable if it's an issue of material constraints on something which would be capable of rolling up. [Answer] So the complexity of a rolling door, like a garage door, is that it must be broken into segments, with each segment being a "leak point" for any leaking air. The most possible configuration today would involve using air pressure to seal the gaps. Basically the rolling door would actually be rather loose around the guide rail, like a garage door. Each slat would have a bit of play to make it easy to roll up and roll down. In a vacuum, this door would simply operate like a garage door in atmosphere. Once the door was closed, however, air would be directed into the air lock. As pressure increases, the slats of the door would be "blown" into the door frame; gaskets along the edges of the slats would seal against the frame and each other. If you want a more secure joint, or something with more control, use magnets. This door still depends on internal pressure to keep the door closed, but uses electromagnets to properly align the slats during the low pressure phase of the door closing. I'd expect there to be a V shaped notch in the rail to "seat" the slat in the proper position. During vacuum operation, the slats only use the rails to keep them relatively in place as they are being rolled up or down. When it's time to seal the door, the slats are rolled down. Just before each slat rolls into it's "home" position (where the notches are), electromagnets are engaged. This pulls the slat into the "notch", ensuring that the slats remain seated in place. Again, gaskets are used to "seal" the slats against each other and the door frame. This has the benefit that no air leaks during the re-pressurization phase, as the doors are "held closed" by the magnets until the air pressure is great enough to do the job itself. Then the magnets can be shut down. Most early space vehicles today didn't run at 1ATM, so you could choose to run a thinner atmosphere mix. An aluminum or synthetic sheet, with ribs to provide structural support, might be "good enough" to keep in air pressure, instead of "slats" in above. Note that there are a TON of reasons why we now use 1ATM on our space vehicles, essentially involving mixing atmospheres while docking and the need to avoid "the bends" when transitioning to an Earth style environment. Your decision on if the added bulk to support a 1ATM Earth-like atmosphere is valid in your universe (as it was an assumption of your question.) Also, you COULD run your shuttlebay at 1/3 of an atmosphere (about the top of mount everest), if the shuttles themselves were fully pressurized and docked onto a pressurized port. This would protect from explosive decompression (the crew could survive the decompression) of ships and space suits while repairing the ship. There's a lot more engineering to think about doing this, however. If you don't mind the door being a bit ridiculous... you could use a large balloon, maybe. I'm not an engineer, but I imagine a large balloon, which can be pressurized to 2ATM. When it's time for the door to close, the balloon is inflated; it's slightly larger than the door it's sealing off, so the balloon "seats itself" against the door frame. Guide wires could be on tracks inside the frame to ensure the balloon actually seats against the door. Because there is vacuum on both sides of the balloon at this point, it would grow in both sides, seating itself against the round aperture. Once the seal was made, the cabin could then be pressurized. The balloon itself would use it's higher-than-ambient pressures to "seal" against the portal, which would protect the internal pressure from escaping into space. Because the balloon is higher-than-ambient pressure, internal pressures would not force the balloon out into space. I think this is a silly idea, but it might work. [Answer] The equipment hatch of the containment of an EPR nuclear power plant has a diameter of 8.3 metres and is leaktight at a design pressure of 5.5 bar. The cover is coupled to the inner sleeve using flanges. Two seals are located in parallel between the cover flange and the sleeve flange, which enable the collection and control of leakages. The coupling device consists of hydraulic cylinder clamps evenly distributed around the flanges. Clamp tightening is performed simultaneously in order to ensure that the clamps are tightened uniformly. The tightening force is maintained by screws before the hydraulic pressure is released. No residual pressure remains in the hydraulic circuit. [![equipment hatch OL3](https://i.stack.imgur.com/EO8w8.jpg)](https://i.stack.imgur.com/EO8w8.jpg) The picture (taken from [a TVO press release](http://www.tvo.fi/news/153)) shows the equipment hatch of the nuclear powerplant Olkiluoto Unit 3 (OL3) during tests in 2013. ]
[Question] [ ## Question This is one of a series of questions centered around how an isolated group of people would survive. Each question focuses on a single aspect of survival. Details about the peoples' situation are below: > > In a novel I am developing, roughly 500 people are living on a peninsula. The isthmus connecting the peninsula to the mainland is very narrow, and spanned by a wall, which prevents the people from leaving (there are deterrents preventing them from climbing the wall or otherwise circumventing it). They also cannot swim around the wall. This also means that no land-based animals can cross onto the peninsual from the mainland. The inhabitants have to live with what they have. For the sake of details, assume the peninusla is roughly the size, shape, and location of [Mahia Peninsula](https://en.wikipedia.org/wiki/Mahia_Peninsula). > > > This particular question deals with armor. The people on the peninsula are all in one village, so there are no wars, battles, or the like. Nothing larger than the occasional brawl. However, the inhabitants do need at least three suits of some type of armor. This armor will be used in a 1v1 battle against a strong opponent with a heavy metal sword, similar in construction to [this](http://awoiaf.westeros.org/images/9/98/Bastard_sword.png). The armor needs to be light enough to allow the user to move fairly quickly, while still being as strong as possible. The user of this armor is also using an identical sword to the one mentioned above. Given the resources present, what is the best armor that could be made to fit these needs? Resources present: * No metal. Aside from the previously mentioned sword (which should not be considered in the list of resources), these people have no access to metal. * Hides from Sea Creatures. There are not many land-based animals on the peninsula, certainly no large ones. There are plenty of sea creatures such as seals however, which could provide hides for leather. * Plant life. Probably not the best bet for armor, but an abundance of plant life is available if needed, including pines (largely cedars), bushes, and vines. * Stones. Rock is readily available, as is flint. Not ideal for armor obviously, but could be useful as tools to help create the armor. It should be noted that the technology level of these people is basically bronze age minus the bronze. Without access to metal, they can get only so far. --- ## My Research My first thought was leather armors. I had some doubts about the existence of such armor though, so I did some research. It looks like leather might have been used mainly as support and backing for metal armors. There were no full suits of purely leather armor. That being said, it does seem that leather armor would provide at least some protection, though not against any sharp point. I found a [great article](https://www.quora.com/What-does-leather-armor-protect-against) explaining the uses of leather armor. That being said, is there a better alternative that my people would have access to? Remember that speed is the priority. [Answer] ## Linothorax Composite armor made of laminated linen is a possibility that (arguably) was used in ancient history - [Linothorax in wikipedia](https://en.wikipedia.org/wiki/Linothorax), [a longer description published in New Yorker](http://www.newyorker.com/books/joshua-rothman/how-to-make-your-own-greek-armor). That would be armor that can offer at least some protection, but can be made without metal from essentially many layers of linen bonded with glue. Of course, the major protective item in this situation is going to be a good shield. [Answer] Have you considered paper armour? If you have access to plants, you can compress their fibres to make stacked paper armour. In fact, [MythBusters once did a segment on this](http://mythbusters.wikia.com/wiki/Paper_Armor_Myth), and ended up classifying the myth as plausible. The armor test compared 1⁄2 inches (13 mm) of paper folded to make armour versus 1⁄32 inch (1 mm) of steel armor. The results were that the paper armour actually works well against most attacks (Including swords), except blunt force attacks and modern day pistols. It's very lightweight as well, allowing superb mobility to most hard-armours if you layer the paper armour correctly (Scales on a fish style). You may also be interested in reading [this link](http://mandarinmansion.com/articles/Chinese%20Paper%20Armour.pdf) for information on variants of paper armour such as paper layered with cotton. [Answer] Instead of armor direct, consider a cloak. A good cloth cloak can be used to entangle weapons. It also adds bulk to the defender, making it harder for the attacker to identify critical parts of the body... and sometimes miss altogether by striking the billow of the cloak instead of the defender. For details of using a cloak as a shield, please take a look at this answer: [Wearing a cape during combat?](https://worldbuilding.stackexchange.com/questions/33059/wearing-a-cape-during-combat) [Answer] What kind of animals live there? Maybe they could create carapace armor from large crustaceans. The Tasmanian Giant Crab grows a torso width of up to 46cm and the Japanese Spider Crab of up to 40cm. American Lobsters can reach a body length of 64cm so I'd assume one could create a somewhat useful carapace armor from a few of those. They'd probably not be very effective against the right swing of a steel bastard sword but I assume they could be more efficient than a sole leather armor. Especially when leather lined. Besides, European swords were created to penetrate steel armor disregarding their agility restriction. Agility against a slow but heavily armored enemy is less useful anyway if it keeps you from handling a weapon able to do any damage to him. So, as they do not wear armor but swing a not so much agile sword, your best option to counter them would probably to be quick and agile and outmanouver the enemy and attack with a lighter weapon like a middle eastern sabre or a small short or broad sword or anything like that. ]
[Question] [ Let's imagine a near future where mankind starts to expand into the solar system. For various reasons, some humans start to be born and raised in space, in zero gravity and micro-gravity. What characteristics could these humans have? For a list of negative points, it's easy to find: * Weaker immune system * Muscle atrophy * Bones atrophy * Motion sickness on earth * Eyesight affected * Puffy face and so on So basically, life on earth is going to be hell for these people, and they will need extended medication just to be able to survive. I want to imagine reasons that could counterbalance these points and make these persons extremely valuable to a space program. I want to point out that I'm not necessarily looking for very realistic answers, (I intentionally avoided using the hard-science tag) but more for coherent ideas. I came up with some ideas already: * Most of the negative points above wouldn't be a problem in zero gravity * Better 3D motion * More tolerant to nervous stress * Higher IQ * Shorter sleep time * ... So my question is: What ideas can you find to develop this list? What traits could make a human better suited for space exploration? [Answer] In no particular order: * Lack of claustrophobia or fear of deep space. * Less prone to loneliness. Would feel at home with a small number of people in a can in the middle of the vacuum. * Instinctual grasp of gravity free, mostly friction free Newtonian mechanics that most people in space have to overcome. * Better sense of direction in space environments, and of distance and direction in space navigation. * Tolerance of cosmic rays (those who lacked this might not have been viable and would have miscarried or been stillborn). * Cosmic ray exposure of parents and child could be mutagenic. Mutations that might be useful could include an additional set of cones to expand vision into the ultraviolet or infrared, or perhaps to have acute visual sensitivity to non-luminous matter (e.g. space dust and asteroids) on nearly black backgrounds (e.g. by briefly obscuring stars) and distinctions in very low light almost black on black scenes. Sense of smell might be further diminished to capture a smaller variety of smells, in exchange much like it was when our primate ancestors traded smell for color vision. * Another mutation that might be useful would be to reactive the mammalian hibernation instinct. Lots of times in deep space, an ability to minimize one's life support drain and boredom in long boring stretches would be very adaptive, particularly if key life support systems (e.g. food supply garden failure or air purifier capacity) were degraded on a long trip between stations - those with the mutation would be more likely to survive. * Space natives would actually likes the taste of the food that is practical to make in space and would probably be innovative in creating new dishes that put the available ingredients to their best advantage. * Subconsciously acutely sensitive to when all is right in space stations and space ships and when things are awry and what might be wrong based on subtle sound, vibration, temperature, humidity, smell, air movement, etc. cues that someone who hasn't absorbed every last detail of those since birth would miss. This would present as a highly intuitive harmony with their space environment. If something is broken, they'd be the first to know that something was amiss, the first to figure out specifically what was amiss, and the first to figure out how to fix it. * Ability to use breath, subtle body movement of body and clothing, and natural drafts on ship to achieve something more like flying and less like floating. * More intuition and experience with what works and what doesn't in zero-G hand to hand combat. * Immunity to pathogens that aren't present in space is no big deal. * Assuming that their parents' employer has a legal obligation to them, it would be cheap to keep them in space where their bodies could cope and expensive to both travel down the gravity well to Earth after a long trip to Earth in the first place from somewhere else in the solar system, and then once the child arrived, they'd have to pay a lot to create an environment where the child could cope. It would be cheaper to keep a potential part of the labor force that was cheaper to maintain in space (due to lack of muscle/bone development, lack of immunity, etc.) than on Earth. * Living in space would leave you without a lot of demand for personal possessions let along something really expensive like real estate or a formal college education. If the space child didn't have many things that money could be spent upon, the desire for the spending wouldn't come into being and they wouldn't have to pay the space child very much money. [Answer] One important characteristic required for human colonization is the psychological profile. Humans who have been born in space may have a very different idea of space to those born on a planet. Instead of seeing space as a place to be travelled through, to them it is "home". They don't have a desire to return to a particular place and so can cope better with being cooped up in tin can. There might however be conflict with those born on the planet, especially if the planet born humans have a position of seniority (real or assumed) ]
[Question] [ What are some ways I can corrupt the government of a country's capital city in such a way as to give a small social group power but still maintaining the illusion of a democratic republic? It would preferable to do this in a way that wouldn't disturb the rest of the world economy too much. Some more information about my world: No magic, technology comparable late 1800s- running water, steamboats, radio (yes I'm aware this is a bit later),telegraph and electrical lighting in developed areas. Some more information about my city: It is in an equatorial region of the world. Its main exports are spices, coffee, tea, rice, stoneware and earthenware, and some fruits specific to this world. The indigenous people from the area were conquered about 300 years ago by foreigners, but they still make up most of the population. There are three branches of a monotheistic religion present in the city, one practiced by the descendants of the conquerors and two practiced by the descendants of the conquered. The city is on a peninsula that separates a smaller sea from an ocean. The area experiences some piracy, but the main trading partners of the country are on the other side of the ocean. The city is on a river, and the main occupations of its lower citizens are digging clay from the clay flats and working in the factories making the stoneware and earthenware. The voting system is gerrymandered so as to significantly disadvantage the working class. The upper class mainly make money through shipping companies, factories, real estate, and high-paying government jobs. [Answer] ## Elect representatives but construct the election process so each representative is beholden to a small group of oligarchs Checklist of things to do: 1. Promote a very strong government "by the people, for the people" ethos and ensure regular and "fair" elections. This will help preserve the appearance that "the people rule". 2. Make it very difficult for prospective representatives to win elections without considerable bankrolls. Perhaps this could be done by demanding expensive ads campaigns. Under no circumstances permit the government to give each candidate some money to fund their campaign. Make contributions by wealthy donors to these prospective reps be completely legal. 3. Organize voting districts as much as possible to vote corrupted representatives into power and keep them there. 4. Suppress, "legally" and quietly as much as possible voting blocks that will not support the oligarchy. 5. Make minor small economic concessions to keep the populace happy. Cater as much as possible to the non-economic values of the voting block that usually votes pro-oligarchy. 6. Sell the poor portions of your population on the lie that "wealth trickles down" and that by allowing the rich to keep getting richer, their lives will get better too. 7. Find a portion of voting public that really hates another portion of the population. Exploit this hatred as much as possible to vote in candidates who can speak to this hatred but who's sole objective is the maintenance of the oligarchy/corrupt ruling class. If the ruling party can do most of these things, they can be assured an almost uninterrupted period in power, provided that the unwashed masses don't get completely fed up with them and there's a revolution. [Answer] 1. Voting a. Undesirables You know, everyone can vote. Naturally not criminals (If you have a significant amount of people in prison and you treat them really badly, let them voting is a bad idea). And not women, they are much too uninformed for such precious decisions. This means also idiots, crazies and uneducated people. And not people doing nothing for their country such as military service. Nothing of it is invented, such systems existed. b. Restrict candidates or allow the system to include unvoted candidates. You can restrict some politicians by including several other conditions, e.g. in Germany the president must be at least 40 years old. Some of our oddities in Germany is the Landesliste, which allows politicians to enter service just by their affiliation to the party winning votes. Nobody voted them in. This is one severe defect in the voting system. You can work on it and allow that parties include people which are automatically voted in and therefore have control over the personal. c. Proportional votes to influence / power. During the early phases of democracy there were systems allowing important persons getting more votes. 2. Power a. Voting is a facade The people have no real power, they are essentially deprived because what they say will be only executed if the real power people agree. Otherwise their instructions will be ignored, forgotten etc. Some people may have enough charisma and power to break out of this constraints, which leads us to... b. Russian dismissal "Hello, friend. We heard that you are unhappy with the current conditions. Please do not rack your brain about such unimportant problems. Everyone here is quite happy the way it is. Please allow us to give you...a gift. A gift from well-meaning friends. Wait, you do not want it ? Hmm, you know that it is a dangerous city here, one of your predecessors was unfortunately rolled over by a coach. Please think it over." [Answer] Pick the people who pick the people See to it that all officials come from one of a small group of parties, and be sure that the selection committees of those parties are ultimately chosen by those selection committees. Now host a club where the important members of those committees might relax without being bothered by people trying to get names before their committee. Let the plebes vote however they want, Kang or Kodos doesn't matter, the deathray still gets built. Let the politicians scheme to get their names before a committee or to discredit their rivals, even hold elections to the committees so long as the candidates are vetted first. Good polling data would be essential to be able to offer plausible losers. Work the people who do the work A few people get elected, they look good making speeches. Some people get appointed, they are good at having opinions similar to the speech makers. A lot of the rest of the government passes paper, making reviews of reviews of studies of studies. As one might imagine many decisions of appointees are made by expert advice as read by a bureaucrat. Now if they get to talking the might see the power of unionizing, but anyone with a head on their shoulder (and planning to keep it there) will know that it might be taken as a coup if they directly use their power. This leads to small group meetings and training sessions provided by Government Works Professional Society. Whose board of directors are often retired from government service. The mid-level workers get indoctrinated on how to save the nation from the follies of speech makers and their pawns. Some projects get lost in the shuffle or have critical flaws discovered while it turns out after reading source some previously rejected plans may be a good idea after all. [Answer] The Voting is a facade. Like a wrestling match the election results of already been decided long before the race begins. The whole election is only done to distract the people from the real issues. The president himself as a figurehead those who really have power as his cabinet which thanks to some laws that passed Remains the Same no matter who becomes president. The legislative brach member can be bullied into following whatever the cabinet decides either by threat of violence or black mail. [Answer] Convince the leaders of the major parties to arrange the election results. An historical example of the Voting Is A Façade expressed in other answers: The Bourbon Restoration in Spain, in the last quarter of the XIXth century. After the military coup that put the 1st Republic out of its misery, the leader of the Conservative party contacted the leader of the Liberal party and they agreed on the system of turnism. The system would consist in both major parties taking turns in the government. When they decided it was the time to switch, the party in power would cede the government to the other peacefully and then the elections were rigged to give the new government enough votes to rule. ]
[Question] [ ## Humans as Ambush Predators Homo sapiens and many of our ancestors practiced a form of hunting known as [persistence hunting](https://en.wikipedia.org/wiki/Persistence_hunting) where we just walk after an animal till it keels over dead from exhaustion. Alternatively, there is [ambush predation](https://en.wikipedia.org/wiki/Ambush_predator) where the hunter attacks prey from a concealed location or sneaks up on prey. Granted, humans are capable of both types of predation but are morphologically best adapted to the former. So, let's say that evolution went a different way. Instead of humans as pursuit predators, humans turned into ambush predators. How are they morphologically different than their pursuit predation cousins? Requirements: Homo pouncus must still be a tool user and tool maker. Physical appearance can be whatever best facilitates ambush predation. The common ancestor between homo pouncus and homo sapiens is [australopithecus africanus](http://humanorigins.si.edu/evidence/human-fossils/species/australopithecus-africanus). Scope: This question is limited to only physiological differences between a pursuit predator human and an ambush predator human. How this human may have evolved or how their psychology might differ our own are both outside the scope of this question. [Answer] I don't believe there would be a difference. Humans are highly adaptable. Ambush predation is something that we already can do. As AndreiROM pointed out in the comments we've been using this technique to hunt each other, specifically in guerilla warfare. I believe that this is less a physical adaptation and more a strategic adaptation. If you mean laying in wait for prey and quickly striking, yes, we already do that--and hunters have for a long time, simply by making an area attractive to prey or waiting in an area that is attractive to prey. This is something we already do. Turkey hunters use camouflage and stealth more than they use pursuit predation, as do deer hunters (who use deer stands and salt licks). This is simply the modern version of what humans already have done for centuries. We also use pursuit predation, but we have been using ambush predation at least as long as the other. [Answer] Easy: the fixed/fused mid-tarsal arch. The fixed arch shape to our feet is the secret sauce to our hyper-efficient endurance running and predation. If the mid-tarsal joint were flexible and our heel bone extended, and our bone thickness/muscle quality closer to that of a Neanderthal/primate, the average 'person' could smoke Usain Bolt because of the extra lever action of the foot and calf... however, they wouldn't be able to do it for very long. Consequently, its much better suited to rough terrain. Your whole foot can 'grip' the ground like your hand can grip. (Imagine if your whole foot could curl forward and grip stuff from the pointed top of the arch of your foot!) I mentioned muscle quality before... the whole fast/slow twitch muscle ratio would be different. We'd have less endurance oriented slow twitch mass and more speed/power optimized muscle mass. Eyesight would still be binocular, but if we're going to be ambushing things, it makes more sense to do that at night. I imagine our senses would remain keener as well, since we would be relying on close-quarters assessment and rapid engagement of prey. [Answer] The concept is quite broad, so I will try and go on with some of the very many possibilities. Considering that the sister sideline had branches off so far back as Australopithecus, it would mean that sophisticated hunting tools like bows and arrows, blowpipes and atlatls are completely out of question. Those people could use simple stone-tipped spears or clubs, but anything beyond that would be highly unlikely. * The posture would probably be generally more crouching than straight. This would help in staying undetected while stalking the prey. Crouching posture has some thorough implications about the skull-backbone joint position and face structure. I will not go into the details here as it would make the answer too lengthy. * The legs would be shorter, but more stockier. Most ambush predators have this type of leg structure which is highly suitable for short speed bursts but not very good for long marathons. The best example is a comparison between [ancient sabretooth cat lineages](http://www.prehistoric-wildlife.com/articles/false-sabre-toothed-cats-the-nimravids-and-barbourofelids.html) and modern cheetahs. Their leg bones were shorter but sported really thick set muscles, highly suitable for quick, lethal chases. The modern cheetah has longer and more slender legs, suited for long runs in open plains. * Also considering that the Australopithecines were not notable masters of wielding tools, the hand structure of your humanoids would be different from our hands in that their hands would not have opposable thumbs. At least not to the degree of our thumbs. They would be able to hold things, but precision grip would not be their thing. * If the humanoids were not as social as primitive homo genera, the canines would probably be longer and more prominent than our or neanderthal canines. These would be uses more commonly for power and aggression display between males, instead of actually using those teeth to bite down on prey to kill it. * An interesting scenario could be if your humanoids pounce on their prey from tree branches, instead of chasing them for short distances on the ground. In this case, the arms would be longer than the legs (for swinging between the branches). Also, their heights would be restricted to no more than 3-4 feet at most, as tall heights make it increasingly harder to move in the canopy of trees. ]
[Question] [ Banks provide many services to the economy, including but not restricted to: liquidity, a safe place to store money, and the ability to move money around and paying bills without having to cart around loads of cash. In turn, Banks profit from the interest generated by the money they move, and, to a lesser extent, from the fees they charge for providing those services. Now we assume a world similar to ours in the fist half of the 20th century, the years after the great depression, with the following differences, if they matter: * There was no Nazi rise to power in Germany. Germany is still struggling with the aftermath of the last war and there is much dissent and unrest, but no one single movement has been able to capitalize on it. * There was a soviet revolution, but the [Russian Civil War](https://en.wikipedia.org/wiki/Russian_Civil_War) following it lasted two more years, and ended in a pyrrhic victory for the reds that left the new soviet union much more weakened. * The United states suffered much more due the great depression. * There is no world war II (for now). After the depression, there was a number of initiatives to [change the economy](https://en.wikipedia.org/wiki/Monetary_reform) and some of them gained a foothold. Some of those ideas included really low [interest rate ceilings](https://en.wikipedia.org/wiki/Interest_rate_ceiling) to, in some cases, complete abolition of interest. However, this eliminated or greatly reduced the income of traditional banks. As the economy still needs the services they provide, is feasible that, in case of necessity, most countries would assume these service themselves, in the way of national banks maintained by a mix of public money and fees. I am aware that there is non-interest based banking, like the Muslim banks and the profit-and-loss-sharing (PLS) paradigm they use, but that is a relatively new thing for banks (in the sense it appeared later than the period I'm using). In this world that role would be covered by private investors (individual or companies). In this scenario, would the existence of private banks still make sense? If they still existed, what would be their sources of income? [Answer] Payment Systems In countries in the civil law legal tradition (not just Europe but also most of Africa, Asia and Latin America), as opposed to the common law legal tradition of England, the "payment system" aspect of banking is generally handled primarily by the postal service and involves "push" transactions (the European name for them is giros) that are the moral equivalent of a money order as opposed to checks in the common law tradition which "pull" money out of a bank account whose balance is confirmed when the check is presented by the recipient for payment rather than when the instrument is issued the way that a money order would be. We have private money transfer systems in the U.S. that operate more or less the way that a European postal account system does, the most famous being Western Union. Debit cards are also conceptually like European postal account systems because the available balance is confirmed before the payment is made and involves a reduction of a positive balance, rather than an increase of a negative balance the way that a credit card does. For larger transactions, wire transfers via banks are the norm, but wire transfers unlike loans and check transactions, are not functionally extensions of credit to the customer. In both the postal systems and in private money transfer systems, there is usually some sort of fee charged to finance the operation, which is some combination of a monthly account fee, a flat per transaction fee, and a fee that is a function of the amount of the transaction. A related line of business common in developing and third-world countries is that of a money courier, who physically delivers cash in person from a sender to a buyer for a fee, usually as an independent business person. Often money couriers network with each other so that a U.S. courier might deliver funds from an Algerian courier in exchange for the Algerian courier delivering from bound for Algeria by the U.S. courier. The two couriers would trade their obligations with each other rather than the physical cash originally delivered to them. This is basically a primitive form of wire transfer. A slightly more sophisticated version of the same thing is called correspondent banking where someone sets up the moral equivalent of a no interest checking account in several countries and then handles transfers between the accounts. Foreign Exchange The business of exchanging one currency for another that doesn't involve explicit interest is sometimes handled by stand alone businesses but is also commonly handled by commercial banks and could continue to be handled by them. Factoring Another major activity of banks in the early days of banking was a form of secured lending called "factoring". In a factoring transaction, the bank buys accounts receivable from a business in exchange for cash, and the business then uses cash to make purchases. As payments on the factored accounts receivable are received, they are paid over to the bank. The bank pays less than dollar for dollar for the accounts receivable based upon the past history of the business in successfully getting paid by those who owe it money plus an additional profit margin. But, unlike interest, this is a one time transaction that is not dependent upon how long it takes the bank to receive the accounts receivable, and it is generally structured to be non-recourse (i.e. if the bank isn't repaid its cash advance in full that is its tough luck). Investment Banking What you and I ordinarily think of as a "bank" is what is called "commercial banking." There is a kindred finance industry called "investment banking" which lines up long term investments in the stock and bonds of publicly held companies for companies that want to go public or are already publicly held in a process called an "Initial Public Offering" (as distinguished from a secondary sale of a stock or bond from a party other than the issuing company), for a significant fee that is financed with the public offering proceeds. If interest were disallowed or greatly limited, big business would get more of its financing from stock, preferred stock (which is a debt-equity hybrid), and would probably limit debt transactions to "money market" transactions in which big businesses borrow cash at very low interest rates for short periods of time (which even restrictive usury laws might permit) basically for working capital purposes. Trust Management, Safe Deposit Boxes and Cash Management Most banking functions are structured as credit transactions (even deposit accounts are currently merely loans from the customer to the bank). But, not all. Some banks have trust departments that manage money held in trust for others (both conventional private trust funds, usually for family members, and also charitable trusts and accounts such as retirement funds and security deposit funds and monies held in trust by lawyers for their clients), typically on a fee basis that is a function of the amount of assets under management. These can sometimes be invested in real world investments like real estate or leased equipment, as well as stocks and bank deposits. Banks also customarily operate safe deposit boxes and there is no reason that some institution or other wouldn't continue to offer this service. Cash management is what armored car drivers, sometimes affiliated with banks and sometimes as independent businesses do. They drive around, pick up cash received from businesses (and drop off new cash for day to day operations), and get it counted and credited to the account of a business in a manner that is conscious of robbery and embezzlement risks. (This is a booming industry in the era of the all cash legal marijuana industry these days.) Another variation on this involves precious metal depositories and warehouses (including grain silos). In these cases, an institution stores commodities such as precious metals, grains, oil, goods in shipping container, etc. in exchange for transferrable warehouse receipts or similar pieces of paper. Rather than physically transferring 4 ounces of gold to pay for something, for example, you might transfer a receipt for 4 ounces of gold. Pre-Paid Bonds Just because private lenders wouldn't be allowed to charge interest doesn't mean that governments couldn't issue interest bearing bonds (municipal bonds or treasury bonds in current parlance). Indeed, they might even be legal for private parties since these interest rates are typically very low because default rates are very low. Buying government bonds creates a stream of payments in the future. One could trade in government bonds at discounts and premiums as the case might be in order to pre-pay obligations that would otherwise accrue over a period of installments, while receiving some time value of money benefits. This would be indirect interest, but might be allowed if government bonds were exempted. This is a method used now to close out loans in cases where prepayment is prohibited or prepayment incurs a significant penalty, while avoiding any meaningful risk of default because government bonds almost never default. For example, government bonds might be paired with lease to own transactions to discount future payments and close out the deals. Various kinds of bankers and brokers arrange these deals now and private banks might continue to do so. Credit Unions and Mutual Banks The New Deal featured many cooperatives, especially in rural areas, which are businesses owned by someone with a relationship other than as an investor in the business. For example, a mutual insurance company is one owned by its policyholders. Prior to the FDIC, mutual banks (owned by depositors) and credit unions (non-profit banks) were very popular because they were much less prone to taking risky high levels of leverage to benefit the private investors and frequently went bankrupt in recessions causing the loss of bank deposits. In contrast, mutual banks and credit unions, acting in their owner's interests, were much more conservative and rarely went bankrupt even in recessions (often called "panics" at the time). If the FDIC had not been created, a ban on private investor owned banks, but not mutual banks and credit unions might very well have been allowed, and because any excess profits from these institutions benefit account holders, there would be (and is today) little incentive for them to unnecessarily jack up fees or charge unreasonably high interest rates. Non-Bank Credit, Bonding and Letters of Credit You would also expect to see in an economy without significant interest being allowed, an expansion of "trade credit" between vendors and purchasers (e.g. selling goods that only have to be paid for in 30 days), and a replacement of financing transactions with lease to own transactions (now commonly seen in auto financing mostly because it affords business users of leased vehicles more level deductions for tax purposes). Private banks might get into this trade credit economy by offering "bonding services" for private companies. A bonding agreement in this context means that a financial institution such as a bank would promise to pay any lawful debts of the party to which trade credit was extended up to a dollar cap in exchange for a fee. Basically the bank is co-signing your loans. These arrangements are now pretty much restricted to government officials guaranteeing that their services will be lawfully performed and for firms in the construction trades, but the concept would be more widely used if credit from banks for working capital was not as easily available. A subtype of this transaction is mortgage insurance, but bonding is usually what it is called in cases of domestic trade credit and contractual liability guarantees. Letters of credit issues for a fee are a variation on bonding (where the bank actually pays all debts rather than just defaulted ones in the transaction) that are uncommon now except in international transactions but might become common if interest bearing loans were prohibited. You might also see lots of loan sharking and other black market credit transactions. [Answer] What kind of interest? We are used to [Compound Interest](https://en.wikipedia.org/wiki/Compound_interest), but the first "banks" didn't follow that scheme at all. When providing "a safe place to store money" it makes sense to request a a payment proportional to amount stored. This would be renting the space. And it would work as simple interest (not compound). By this logic, simple interest will continue to make sense, as long as there is some money to store or transfer. If you really want to remove that, you will have to remove marginal space requirement for money storage and mitigate the risk of losing the money for the people. That will be done, of course, by removing physical money. I should point out that what makes a bank a [bank](https://en.wikipedia.org/wiki/Bank) – at least in our timeline – is whatever or not the government applies banking regulations to a [financial institution](https://en.wikipedia.org/wiki/Financial_institution). [Financial institutions outside of banking regulation](https://en.wikipedia.org/wiki/Non-bank_financial_institution) may continue to exist. --- For example, it would be possible to create a financial institution that provides credit, just in reverse. Instead of giving you money to buy a good that would generate value for you, and require you to pay back. The financial institution would buy the good and allow you to use it, as long as you continue to pay in installments. The sum of the installments will be more than the value of the good, the difference is how much you are paying for this service. This service would be outside banking regulation, and could have a higher "interest" service cost to good cost ratio than the government would allow a bank. If the person fails to pay, the good belongs to the financial institution, and so they are free to provide the good to another person interested in it. Now, the financial institution will need to provide a good in good condition to the new client, so they will be interested in providing maintenance. It would be expected that financial institutions working by these means may specialise in particular types of goods. And it is called [leasing](https://en.wikipedia.org/wiki/Lease). --- Now, let's say that the interest cap applies to all investments... The idea of paying people interest on saved money is that the titular yields the money which can now be invested in some other activity (for the bank that activity is to loan the money to third party). So, if I can setup a financial institution that takes investments (saved money) and uses them to generate value at a higher rate than government allows to pay back to the investor (interest cap) I will prefer this mechanism over selling stock because I can pocket the difference. If this is viable, fewer companies will play in the stock market, instead they will want to become financial institutions, private financial institutions. In fact, it makes sense to create financial institution that provides this service to other companies. [Answer] There will be a multitude of different solutions, some of which have been alluded to in answers and comments. One early change I can see is the return of "free banking", where individual banks can print money, and their profits/losses are based on their portfolios. It is interesting to note that in the Free Banking Era (between the close of the "Second Bank of the United States" and the implementation of the Federal Reserve), recessions and depressions were much shorter and less damaging to the economy as a whole (a bank failure only affected the customers of the bank and only put the ban's assets at risk). Individual banks will overcome lack of interest earnings through innovative products and services, as well as fees for services (selling products like insurance, safe deposit box fees, accounting fees for customers wanting the bank's staff to do their accounting for them etc.) Banks might also move into brokerage and wealth management services. The other thing to remember is modern banks generally act as intermediaries, gathering numerous small deposits from depositors to create larger pools of money to make available to borrowers. In today's low interest rate environment, "disintermediation" is taking place through the growth of so called "Fintech", where people can join the "[Lending Club](https://www.lendingclub.com)", for example, and personally make loans to individuals and business, negotiating the terms on their own. Since there is no intermediary to pay, the lender can make more money even on a low interest rate loan (no need to pay a cut to the bank). Paypal is another example of Fintech removing a layer of intermediaries to make or receive payments. These services use the internet for ease of use and the ability to harness the power of large computer resources for record keeping, but there is no actual reason this could not be done more slowly via telegraph and an office full of 1930 era "computers" (when "Computer" was a job description and not a machine). So the most probable response is low interest rates squeeze out inefficient banks by removing intermediary income, while banks fight back by becoming financial boutiques offering services you don't get anywhere else. [Answer] ## Socialised Banking No WWII and no rise of the Soviet Union as a world superpower means that the US never experiences the "Red Scare". Because of this the US never has the massive anti-socialist movements that have since prevented socialized programs from gaining a foothold in American Government. As the Great Depression drags on, socialism would gain a lot more popularity in America as people would continue to blame unregulated market forces for the collapse of the economy (which is fair since speculation and unbacked currency DID collapse the economy). When socialism replaces free markets, it normally does so by taking charge of whatever industries are considered most abused 1st. In the case of the US, it would be the financial institutions. Socialised banking does not need to generate any profits, because the nation profits indirectly from taxation. If you get a federal loan to buy a house, then you will pay property taxes on that house. If you get a federal loan to open a business, then businesses profits will be taxed. If you use a federal credit card to buy groceries, then those groceries include a sales tax. Because the government alway profits from money spent, it means it will alway profit from making money easier to spend allowing it to allocate money to maintaining banks as a public service. ]
[Question] [ Closed. This question needs to be more [focused](/help/closed-questions). It is not currently accepting answers. --- Want to improve this question? Update the question so it focuses on one problem only by [editing this post](/posts/55131/edit). Closed 7 years ago. [Improve this question](/posts/55131/edit) In my world , instead of the world being discovered to be a finite planet during the age of discovery , humans discover that the world is infinite. Due to this , the age of discovery never ends , and with it colonization. The constant expansion of states goes on all the way up to the 21st century, with modern communication technology , transportation , etc. My question is: how large could such a modern state get while still being controlled by a single central government? [Answer] Governments can extend their territory as far as they can act and react to things in a reasonable amount of time. A country like the US which has divisions of government would probably be what you'd expect most likely to arise due to the difference in communication and travel, so you'd have a local government and a more expansive federal government more than likely. How big would these be? Basically Multiply the fastest attacker by 3 months... 7,200 km/h is the speed of the fastest attack. 3 months is 2,160 hours. That gives us a size of: A country can be a diameter of 31,104,000 km. An area of 760,000,000,000,000 km^2 or 1,489,986 times the surface area of Earth. the other idea is that countries can hold together so long as they have communication with it's furthest extent, without taking into account it's military assets, within a reasonable time frame. Let's say this is a month, though it might be as small as a week or even a day when pushed to extremes. We can communicate at the speed of light or just about so... 2,592,000 seconds in a month. 299,792,458 m/s is the speed of light. 1,554,124,102,272 km diameter is the max size of a country then. (It would take 25,000 years for our fastest jet to get there, so humans would clearly not be out this far.) It would have an area of 1,900,000,000,000,000,000,000,000 km^2. That's a surface area of 3,724,964,318,762,841 times that of Earth. However, with that, I have to point out that Humans spread outward at about 1 to 4km per year, so going back to about 70,000 years ago when there was only about 10,000 humans on earth we only covered about an area with a diameter of 2,000 km. In the best conditions then humans would have only populated an area with a diameter of about 280,000 km. So if your world is infinite, but follows the same or similar development as ours then the maximum size of a state is an area of 61,600,000,000km^2, roughly 121 times that of the surface area of Earth. And then they'd reach a place where no man has gone before and then you'd have to build up everything past that point. For that, look to the Colonial American era... but that's another question. At this point the question is less about could the "rule" the area to could they "control" the area. Humans would be sparse past that point that while you could patrol it and whatnot, you would miss a lot, especially with nothing built up. And policing really would be a nightmare because people would just keep moving out further and further. It might take years, but people could and would get beyond the borders of possible control, and even if they couldn't, far enough out and even a city would be missible. Patrols for many years would be along thing like the Oregon Trail where people are traveling to in great numbers, not over the whole of the area. For this scenario, I suggest a read of Terry Pratchett's Long Earth Series which discusses a similar idea that you might get something out of it. [Answer] The problem would really lie in defining what is meant by "state." I say this because it is that kind of structural problem which ultimately arises; when you get big enough, it becomes impossible for a central government to rule an empire. Different empires through history have approached this problem in different ways, broadly-speaking. Let's look at a few: * The Romans * The Mongols * The British * The Americans The Romans enjoyed one of the oldest massive empires we know of; at its height, far before widespread literacy, mass media, or nationalist sentiment, the Roman Empire sprawled across three continents and commanded nearly half of the world's total human population. Worth mulling over a bit, I think. Anyway, this empire ruled from a central site (Rome), but to keep command of its far-flung peripheries, it delegated leadership to "client states" - that is, nominally in Egypt, for example, Egyptians might still rule at many levels of government, but there would be a Roman citizen near the top whose job it was to ensure that the wishes of the Empire were carried out by the local rulers. Later in its history, under immense pressure to deal with problems all along its very long borders, Rome split into two separate empires - the West and the East. This was, realistically, never going to be made whole again, because people are as people are, and no one would easily give up command of half the greatest empire the world had ever seen. The Mongols came later and did things differently. They ended up controlling a much larger area of the earth, but not necessarily a larger part of the population; while a larger number of people possibly lived on the lands they claimed, the Mongols didn't really ask a whole lot of those populations once they owned them - they killed quite a few and did relatively little with them once they had them, save perhaps levy taxes, to be carried out by, again, local leadership, this time without even necessarily a Mongol citizen in place - instead the threat of the Mongol Horde was deemed sufficient to coerce behavior friendly to the empire. The Mongols ruled via these mobile armies first and foremost, and it makes clear that you can control vast territories and resources without "you" (that is, the citizens of your empire proper) being very large. The technology of the horse makes this possible for those willing to exploit it fully. The British were exploiting another conveyance - the sailing ship - to rule their far-flung empire of colonial holdings - and again, the question is whether you want to consider all their lands and peoples properly part of the "British Empire" - because they might have "ruled" them, but under the auspices of things like the East India Company, a corporate affair that pretty much managed the Indian subcontinent for them for much of its history within the British Empire. The British are fascinating because I think their empire in many ways models the problems a far-flung spacefaring empire would have to overcome - some of the greatest problems they experienced were the expense of projecting their power overseas, the loyalty of their colonies to their empire, and the communications troubles of such distant holdings. This is a polity that took an entire continent and couldn't do anything with it other than basically use it as a prison for a while. Again, whether we consider all Australia properly "owned and controlled" by the British at all points they claim to have owned it is debatable in my mind. The United States of America, perhaps in response to the the problems of their British parents, had this idea that smaller confederated states should coexist under a federal, central government, which would effectively facilitate the cooperation of the state governments, which were themselves the thing seen more close to countries in their day. The "nation" of states which you sometimes hear the founding fathers of American government refer to encompasses this plurality, and indeed you can look at the diplomatic, military, and economic dealings of other countries and empires in the world with the early USA and see that there was considerable confusion about whether they were a group of independent states, or whether they were provinces of a larger federal government. That question eventually [got resolved in a pretty nasty fight about a different but related problem](https://en.wikipedia.org/wiki/American_Civil_War), showing that even this method of controlling vast numbers of people and tracts of land has its pitfalls - namely, that if you enfranchise most of your highly heterogeneous population, there will be significant and empire-ending disagreements unless the confederation of states idea is abandoned in favor of a much more powerful central government. This then suffers the same problems as large, centralized empires of the past, but luckily America arises in a period of vastly improved conveyances (steam engines and telegraphs), and these technologies, along with high literacy and "universal" suffrage, allow it to mold a sense of national belonging throughout its population - enforcing its empire from the bottom up more than the top down. Indeed, this worked so well that it became the ultimate model of the modern nation-state; Europe especially quickly succumbed to this nationalism soon thereafter; nothing stands in the way of an empire whose entire citizenry is employed in the cause. This is an excellent reason to reconsider how big an empire truly is based on its method of control; though Mongolia might field a mighty army in terms of raw power and size compared to other feudal states, nothing compares to the kind of massive, million-strong citizen army France could field with its nationalist instincts in full swing, despite a much lower total population. Ultimately, limits on coherent size will depend on the nature of the state in question. A "Mongolia" rule-through-fear and not-caring-ness might yield a very large empire in terms of size and resources, but Nationalist states with modern communications technologies would be the more powerful, more truly populous alternative, however much land they actually owned. Finally, a note on technologies - at a certain point, you will run up against the problem of latency. Even with the internet, you are fighting, ultimately, the speed of light, and it becomes difficult to impossible to communicate with colonies separated from the federal control center without years-long lapses in judgment. The natural response to this will be to delegate, as the Romans did when they were dealing with the latencies inherent to foot and horse travel, and then from those small fractures will arise great schisms which will shake your nation-states apart one after the other, and the surface of your world will become an infinite Balkans, united only by the effective reach of light speed communications and the rate of change inherent to the forces of disunity they must struggle against to remain whole. Empires might consist of many billions of people and many dozen Russias' worth of landmass, but it is difficult to imagine an order of magnitude larger than that working for very long. [Answer] Very large. World wide governments were impossible until modern transportation and communication. So if you want to find the limits of your empire find the limits of modern travel and communication. The British were able to hold on to empire that was separated by months of sea travel. So take that as your limit but changes sea travel to air travel. An airplane can cross the world in a few hours, obviously an empire that so big that it would take months to cross it by air would be several times larger than the Earth. Of course governing an empire that large would be a super pain, but not impossible. Most likely the empire would be separated into large, mostly self-governing states, all loyal to a central government. [Answer] I think the problem lies on how often a powerful military can develop. There are basically 3 parameters that should be taken into consideration: * Average size of a state * Probability of a state to become one that wants to extensively develop * Time interval and duration for a state to be externally militarily active The first two parameters are out of my knowledge to answer. I would summarize these 3 parameters into "time interval and duration that one state is externally militarily active in a given area". Referring to [Wykes' answer](https://worldbuilding.stackexchange.com/a/55142/22748) and my own knowledge about Chinese history, in the Eurasian area, which is quite large, I only remember less than 10 times of a state extending its territory extensively. I do not have any actual values, but these parameters can help. Let's not look at how far a state can invade first, but how far a state's technology can reach. I think answering this question should be based on a theory: assuming all humans started evolving at the same time, due to different anthropological factors, some have developed modern technology first. For example, for a long time, most of the world outside Europe had the ability to handle electricity. This proves that this difference can be very great. However, in an infinitely large world, as long as we assume that a certain probability that a country has developed modern technology, there must be multiple countries that developed modern technology as well. Therefore, the only thing that matters is, how far are these countries apart? They must be far enough such that when one country has developed such technology, the other ones must not be close enough to know the technology. In conclusion, from the technological perspective, I am against the answer that a country like this can be infinitely large. We only have one example on our Planet Earth, so there is nothing to fairly compare with. But assuming that Planet Earth is the median example of how human civilization should develop, if we have a planet with twice Planet Earth's size, technology would be developed at the same time at two halves of this planet. In a planet with `x` times Planet Earth's size, we can assume that `x` countries developed modern technology together. From another thought, if our planet is infinitely large, exploration will never end, so explorers will never be satisfied and sit down and start exploiting what it has explored (just like Mongols). So maybe how globalization has developed in the past centuries (after Earth has been proved finite size) would not have happened in this way. ]

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